Peterbilt Headlight Assembly Upgrade & Alignment Guide

Why Upgraded, Aligned Headlights Matter

Properly functioning headlights are critical for truck safety and compliance, especially for Peterbilt fleet vehicles. About half of all traffic fatalities occur at night or in low-light conditions, making headlight performance a life-or-death matter. Brighter, well-aimed headlights improve driver visibility and also prevent glare that could blind oncoming drivers. They help you spot obstacles, road signs, and pedestrians sooner; In fact, studies show vehicles with high-performing headlights experience significantly fewer nighttime crashes.

Beyond safety, regulatory compliance is a factor: the DOT’s FMVSS 108 standard requires headlights to meet certain brightness and aim criteria. Misaligned or underperforming headlamps risk failing inspections and can even incur fines if they grossly violate glare limits. For fleet managers and owner-operators, maintaining upgraded, correctly aligned headlights on Peterbilt trucks is essential for safety, legal compliance, and driver comfort during night operations. In short, better headlights let you see farther and react faster, reducing accident risk while keeping everyone on the road safer.

Headlight Options: Halogen vs. LED vs. HID (Pros and Cons)

When planning a Peterbilt headlight assembly upgrade, you’ll typically choose between halogen, LED, or HID lighting. Each technology has its pros and cons:

• Halogen Headlights: The long-time standard on trucks, halogen bulbs are inexpensive and easy to replace. They use a tungsten filament in halogen gas, producing a warm (~3200–3400K) yellowish light.
  • Pros: Halogens are affordable (often $10–$20 per bulb) and proven. Their lower brightness means less risk of blinding oncoming traffic, and they’re plug-and-play on older Peterbilt wiring with no extra components needed.
  • Cons: They have limited output and lifespan. A standard 55W halogen produces around 1,000–1,500 lumens and lasts roughly 500–1,000 hours. That means dimmer illumination and more frequent bulb changes. Halogen light also tends to degrade over time (filaments dim as they wear).
• LED Headlights: LED (Light-Emitting Diode) headlights have become the top choice for modern upgrades. LEDs emit a bright white light (~6000K) and reach full brightness instantly. Overall, LEDs offer the best illumination, longevity, and efficiency; making them a worthwhile investment for serious truck operators.
  • Pros: They are far more energy-efficient than halogens, often drawing about half the power for the same or greater light output (for example, ~22W vs 41W in one comparison). This efficiency reduces strain on your truck’s electrical system. High-quality LED bulbs or sealed-beam replacements can produce 6,000–8,000 lumens per bulb, making them 300–400% brighter than stock halogens. This dramatically improves night visibility for the driver. Another major benefit is longevity: LEDs often last 25,000 to 45,000 hours, essentially the lifespan of the truck. In practical terms, that’s 15–20 years of use, compared to maybe 6–12 months for a halogen bulb. LEDs are also more robust. There’s no delicate filament and they handle vibration well (important for big rigs). 
  • Cons: Upfront cost is higher; complete LED headlight assemblies or kits are pricey (though prices have been dropping). Some retrofit LED bulbs may require additional components like anti-flicker resistors or CAN-bus adapters to work with the truck’s wiring (to prevent bulb-out warnings or flicker in trucks with daytime running lights). Also, poorly designed or non-DOT-approved LED kits can produce glare if not properly aimed, so stick with DOT-compliant LED assemblies. 
• HID Headlights: HID (High-Intensity Discharge) or xenon headlights were popular in luxury cars and some aftermarket truck upgrades before LEDs took over. HIDs produce an extremely bright, white-blue light using an electrical arc through xenon gas. They can output more lumens than halogens (and comparable to LEDs) while drawing less power than halogens.
  • Pros: Very bright, with a crisp beam; long life (~2,000–3,000 hours for many HID bulbs, and up to 15,000 hours in ideal conditions); and a whiter light (~4300K–6000K) that can improve contrast. LEDs have largely surpassed HIDs for aftermarket upgrades because they offer similar or better brightness without the downsides.
  • Cons: HIDs require separate ballasts and high-voltage ignitors, adding complexity to installation. They also have a brief warm-up time to reach full brightness (a few seconds), unlike instant-on LED/halogen. Improperly fitted HIDs in halogen housings can cause excessive glare, so they must be installed in proper projector lenses or assemblies designed for HID to remain road-legal. Additionally, HID components (bulbs and ballasts) are relatively expensive to replace, and failures can be more common in the harsh vibration environment of a truck. You may still encounter HID kits for Peterbilts, but be sure they are DOT-approved and properly aimed if you use them.
    

For most Peterbilt headlight upgrades, LED assemblies are the top choice due to their superior brightness, longevity, and efficiency. Quality LED headlights (from brands like JW Speaker, Truck-Lite, or United Pacific) are built for heavy-duty use and offer the best performance improvement. Halogens remain a budget-friendly and reliable option if cost is the main concern, but expect to sacrifice brightness and change bulbs more often. HIDs can be an intermediate step up in brightness, but given the rapid advance of LED technology, many fleet managers are skipping HIDs entirely in favor of LEDs. Whichever you choose, make sure the headlights are SAE/DOT compliant and designed to fit your Peterbilt model for a safe, legal upgrade.

Model Fitment Chart: Peterbilt Headlight Applications by Model & Year

Peterbilt has produced various models over the years, and headlight assemblies differ among them. The guide below covers major models (379, 389, 579, 330, 337, and 367) and their typical headlight configurations and year ranges:

• Peterbilt 379 (1987–2007): The classic 379, produced from 1987 until it was retired in 2007, originally came with dual rectangular sealed-beam headlights on each side. These are the familiar 4×6″ halogen sealed beams (two per fender) with separate high and low beam units. In later years and special editions, some 379s had single large rectangular composite headlights or even aftermarket round conversions, but dual rectangles are most common.
  • Upgrades: You can replace the 4×6″ sealed beams with LED sealed-beam units (direct swaps) or retrofit a conversion housing to use H4 halogen/LED bulbs for more light. Many aftermarket kits are available to give 379s dramatically better illumination while preserving the classic look. Always verify that any LED sealed-beam replacements are DOT-approved for on-road use.
    
• Peterbilt 389 (2006–2024): The 389 succeeded the 379 as Peterbilt’s flagship in 2006, carrying forward the traditional styling with some modern touches. The 389 (and its sibling the 388) features dual round headlight pods mounted to the fenders. Each pod typically contains a high-beam and low-beam round lamp (about 7″ or smaller) behind a curved lens, often with an integrated turn signal. The factory 389 headlights were halogen, but LED pod assemblies are available as direct replacements. In fact, Peterbilt’s new Model 589 (the 2024+ successor) introduced all-LED pod headlights, which use 30% less power than the old halogens.
  • Upgrades: Owners of 389s commonly swap the stock halogen bulbs for LED bulbs or replace the entire pod assembly with LED projector units for better light output. Aftermarket LED pod assemblies (from companies like Truck Lite, United Pacific, etc.) offer plug-and-play installation and can dramatically improve brightness. The 389’s headlight design is also shared with some vocational models (the 567, and 388). This means many 389 LED upgrade kits will fit those models as well. Ensure any new assembly’s mounting and connectors match the 389’s harness, and remember to re-aim the lights after installation (the 389 pod lights have adjustment screws just like the older models).
    
• Peterbilt 579 (2012–Present): The Model 579 is Peterbilt’s ultra-aerodynamic highway tractor, introduced in 2012. It uses a completely different style of headlight assembly: a sleek composite headlamp molded into the aerodynamic hood shape. The 579’s headlights typically have a complex multi-reflector or projector design behind a polycarbonate lens, with an integrated LED daytime running light strip on newer models. Early 579s came with halogen projector low beams and H11/H7 bulbs, whereas mid-cycle refreshes and the latest UltraLoft versions offer OEM LED headlight options.
  • Upgrades: For 579s with halogen projectors, you can upgrade the bulbs to high-performance halogens or HID/LED conversions designed for projector housings. (Be careful to use conversions that retain a proper beam pattern to avoid glare.) There are also aftermarket LED projector headlight assemblies made for the 579. These are direct replacements that swap in the entire unit for a true LED solution. When upgrading a 579, check the year range compatibility: 2012–2017 models may use a different headlight unit than 2018+ models (due to design refreshes). Always confirm fitment by year and whether any adapter harness is needed. With a quality LED upgrade, a 579 can achieve far better nighttime visibility and a modern look, while drawing less power from the electrical system.
    
• Peterbilt 330 (1995–2022, Medium Duty): The model 330 is a medium-duty conventional that saw a long production run. It was first introduced in 1995 and later updated in 2007; production continued through the 2021/2022 model year. The 330 (and its close cousins Model 335 and 340) typically use a pair of composite headlight assemblies mounted in the grille/hood front. On 2005+ second-generation 330s, the headlights are integrated units with clear lenses, housing H4 or H13 halogen bulbs for high/low beams and often incorporating the front turn signal. These are sometimes referred to as “Pod” style or aero composite headlights (though smaller than the 389’s pods).
  • Upgrades: Many aftermarket manufacturers make LED replacement assemblies for the 330/335/337 series trucks. These often fit year ranges like 2005–2015 Peterbilt 330 (which covers the common second-gen design). Check product descriptions closely, as early production years (mid-2000s) versus later (2010s) can have slight bracket or connector differences. In general, if your 330 has the factory composite headlights, you can likely find an LED version that bolts in with plug-and-play connectors. Upgrading will give your medium-duty Pete a huge jump in light output and modernize its appearance.
    
• Peterbilt 337 (2010–2022, Medium Duty): The 337, a Class 7 truck, was introduced in 2010 to replace the older Model 335. It shares a platform with the 330/348, and for our purposes, the headlight setups are similar to the 330 above. A Peterbilt 337 from 2010–2014 may use the same headlamp assembly as a late 330, while 2015+ 337s might have an updated design (for example, when Peterbilt launched newer medium-duty models). Always verify the exact year range for headlight parts: e.g., one aftermarket listing might say “Fits 2010–2014 337” and another for “2015–2018 337.” The differences could be internal wiring or projector vs reflector style.
  • Upgrades: Just like the 330, you have options to upgrade the 337’s headlights to LED or to better halogen bulbs. Most aftermarket LED units for 337 are designed for 2008+ Peterbilt medium-duty trucks. These often come with 9007 or H13 plug adapters to plug into the factory harness. Upgrading a 337 to LED headlight assemblies will provide consistent, bright light and eliminate the hassle of frequent bulb replacements. This is a big plus for a work truck that sees daily service.
    
• Peterbilt 367 (2007–Present, Vocational): The 367 is a severe-service Class 8 model, introduced in 2007 to replace the older 378/357 trucks. It’s often used in vocational roles (dump trucks, mixers, etc.) and typically has a set-forward front axle with a fiberglass hood. The Peterbilt 367’s headlight configuration can vary by specific setup. Some have dual rectangular headlights like the late 378 (one large rectangular unit per side), while others may use the 389-style dual round pod headlights mounted to the fenders. In fact, certain 367s and 365s were delivered with single rectangle lights that look much like a 379’s single-light configuration. This can be confusing, so always check your specific truck.
  • Upgrades: If your 367 has the rectangular composite headlights, you can likely swap in an updated unit (some newer 567-style lights might retrofit, but verify mounting). If your 367 uses the dual round fender pods (which many do, since Peterbilt offered that as a stylish option), then any 389-compatible LED pod assembly will also fit the 367. For example, blackout-style LED pods with DRLs are marketed to fit “Peterbilt 389/367/379/etc.” due to the common mounting. The 367’s electrical system should accept LED upgrades without issue, though adding an anti-flicker harness may be needed if you notice any pulsing when using with daytime running lights. Upgrading a workhorse 367 to modern LEDs is highly beneficial. You get rugged, vibration-resistant lights that can handle jobsite abuse and nighttime highway runs with equal reliability.
    

Fitment Tip: Always double-check part compatibility by model year and VIN when ordering headlight assemblies. Use a model-specific chart or the PeteTruckParts.com Lighting collection to find the exact headlamp assembly for your truck. Peterbilt did occasionally update headlight designs within a model’s lifespan (for example, switching from 2-bulb to 4-bulb configurations, or different connectors), so verifying the year range ensures you get a hassle-free installation.

Tools and Parts Checklist

What’s Needed to Upgrade or Replace

Upgrading or replacing a Peterbilt headlight assembly is a manageable job in a workshop or even roadside with the right prep. Here’s a checklist of tools and parts you’ll likely need before you begin:

• Replacement Headlight Assemblies or Bulbs: Obviously, have your new headlight parts on hand. This could be complete headlight assemblies (e.g. an LED pod for a 389, or a composite lamp unit for a 579), or just replacement bulbs (H4, H7, H11, 9007, etc., depending on model) if you’re only swapping bulbs. Verify you have both left and right units if applicable, and that they’re correct for your model/year.
  
• Basic Hand Tools: Most Peterbilt headlight mounts use screws or bolts. Common tools include:
  
  • Phillips screwdriver (many headlight bezels and retaining rings use Phillips screws).
    
  • Torx drivers or bits (some models like the 389 pod use Torx screws. A T25 Torx is reported for certain 389 headlights).
    
  • Socket wrench set with extensions. For example, a 3/8″ drive ratchet with sockets (sometimes 10mm or 12mm) may be needed for adjustment screws or mounting bolts.
    
  • Allen wrenches if your aftermarket lights use hex-head socket screws.
    
  • Small flat-head screwdriver or pick tool (handy for prying off clips or opening connector locks).
    
• Masking Tape & Marker: If you plan to check or adjust headlight alignment during installation, have masking tape and a marker or pencil. You’ll use this to mark beam centers on a wall for aiming (explained in the alignment section below).
  
• Measuring Tape: A tape measure (at least 25 feet) to set the proper distance for headlight aiming.
  
• Panel or Trim Removal Tools: Some models (like 579) may require removing an access panel or bezel. Plastic trim tools or a flat screwdriver wrapped in tape can help pry off bezels without scratching paint.
  
• Electrical Supplies (if needed): Generally, headlight swaps are plug-and-play, but be prepared with:
  
  • Dielectric grease to protect electrical connections from corrosion when you plug the new lights in.
    
  • Wire connectors or a soldering iron and heat shrink, if any wiring modifications are required (for example, if your upgrade kit includes an adapter harness, you might need to splice it. However, most are adapter plugs).
    
  • Multimeter or test light, to verify power and ground if the new light doesn’t turn on initially (helps with troubleshooting wiring issues).
    
• Anti-Flicker or CAN-Bus Adapters: If upgrading to LED on a truck that monitors headlight circuits, you might need load resistors or CAN-bus adapters to prevent flicker or warning lights. Some LED kits include these. If yours did, have them ready to install as per instructions.
  
• Mounting Hardware: New headlight assemblies often come with new hardware (screws, brackets). However, it’s wise to have some spare nuts, bolts, and washers that match the originals. Stainless steel hardware is recommended for exterior use. Also, retain any specialty brackets from the old lights if the new kit didn’t include them.
  
• Personal Protective Equipment: Safety glasses (when drilling or working under the truck), gloves (especially when handling halogen bulbs. The oil from your skin can shorten bulb life, plus gloves protect you from sharp edges.), and possibly a fender cover to protect the paint when leaning into the hood area.
  
• Work Light: An auxiliary work lamp or flashlight can be very helpful so you can see what you’re doing behind the headlight buckets or inside the hood, especially if you’re working in dim conditions or at night (which is ironically when you might discover you need a headlight replaced!).
  

Having all these tools and parts ready will make your headlight upgrade go smoothly. Preparation is key. You don’t want to be scrambling for a tool midway through or find out you’re missing a connector when the truck’s headlight is already apart. It’s a good idea to lay everything out and even do a quick test of the new lights (if possible) before uninstalling the old ones. For instance, you might plug a new LED headlight into the harness without mounting it, just to ensure it illuminates properly (test both high and low beam) before doing the full install.

Step-by-Step Removal and Installation Instructions

Replacing a Peterbilt’s headlight assembly can vary slightly by model, but the general process is similar. Below is a step-by-step guide that covers the typical removal and installation. Always refer to your model’s service manual if available, and follow any specific instructions that came with your new headlight kit.

1. Park and Prepare the Truck: Park the truck on a level surface and engage the parking brake. For added safety, turn off the ignition and disconnect the battery (at least for the circuit you’re working on) to prevent any electrical short while working on the lights. If you’re just changing a bulb, you can usually get by with the battery connected (lights off), but for a full assembly swap it’s safer to cut the power. Make sure the engine is cool if you’ll be leaning into the engine bay (especially on a 579 or similar where you need to open the hood). Also ensure you have adequate lighting to work, or do it in daylight.

2. Access the Headlight Assembly: This step differs by model:

• On 389/379 and similar with external headlight pods: You typically access the mounting bolts from the outside. For example, on a 389’s round pod, you’ll remove a chrome bezel or ring. Often there are a couple of Phillips screws holding a trim ring around the headlight. Remove those screws and the trim ring. This exposes the sealed beam or bulb unit. For dual round lights, you may need to remove the upper to get to the lower. The pod housing itself is attached to the fender by a few bolts (accessible on the underside or inside of the fender). Consult the 389’s manual for exact bolt locations. Usually 3 or 4 bolts secure the pod. Use a socket and extension to reach up under the fender to those nuts if needed.
  
• On aerodynamic models (579, 387, etc.) with integrated headlights: Open the hood. You’ll likely find an access panel or simply reach behind the headlight from the engine bay side. In some cases (579) there may be a rear cover you twist off to get to the bulbs. If removing the whole assembly, there will be mounting bolts (often 3 or 4) around the perimeter inside the hood structure. Remove any plastic splash guard or cover to reveal these. A ratchet with an extension is useful here.
  
• On medium-duty (330/337): Open the hood; the headlight assemblies are in the grille/hood front. You might see retaining bolts on the back side or sometimes from the front. Some have a bezel on the front you unscrew, then the headlight unit comes out the front. Others come out from behind after removing retaining screws.
  

Take care to support the headlight as you remove the last fastener so it doesn’t fall and yank on the wiring.

3. Disconnect Wiring: Once the assembly is loose, unplug the wiring harness. Most Peterbilt headlights have a multi-pin plug (e.g. a 3-pin for H4, or separate connectors for high, low, turn signal, etc.). Press the tab on the connector to release it (sometimes a small flat screwdriver helps to depress a stubborn tab). If the connector is tight or slightly corroded, wiggle it gently. Avoid pulling by the wires. If you have auxiliary lighting like an integrated turn signal or marker in the headlight assembly, disconnect those as well (some use wedge bulb sockets you twist out). Note: It’s wise to inspect the wiring at this point. If you see green corrosion or heat damage on the connector, consider replacing the pigtail now to ensure a good connection for the new light.

4. Remove the Old Headlight Assembly: With wiring disconnected and all fasteners removed, take out the old headlight unit. Keep an eye out for any spacers or brackets that might fall off. Sometimes there are special mounting brackets, aiming screws, or retainers that you’ll need to reuse. For example, older 379 dual-square setups have an inner bracket holding the sealed beams. Make sure to retain that if the new assembly doesn’t include it. Clean the mounting area of any dirt or rust. This is also a good time to check any headlight bucket drains (some have small drain holes for moisture) and clear them if clogged.

5. Prepare the New Headlight: Before installation, prepare your new headlight assembly:

• If it’s a full assembly, compare it side-by-side with the old one. Verify mounting tabs, screw holes, and connectors match up.
  
• Transfer any parts as needed. For instance, some aftermarket lights require you to use the old mounting bracket or aiming screws. Swap those over now. If your new assembly has adjustable aiming screws, check that they’re preset to roughly the same position as the old (this can help the initial alignment be closer).
  
• If you’re installing new bulbs into a housing, do that now. Important: Do not touch the glass of halogen bulbs with bare fingers. Use gloves or a clean cloth. Oil from skin can cause hot spots and bulb failure. If you accidentally touch the bulb, clean it with isopropyl alcohol and a lint-free rag.
  
• For LED kits with external drivers or resistors, mount those securely. Many kits come with 3M tape or brackets to secure the LED driver “box” inside the hood or behind the headlight. Choose a spot away from moving parts and where it won’t collect water. Zip-ties can help secure wiring out of the way.
  
• Apply a dab of dielectric grease to the connectors to prevent corrosion and ensure a solid electrical connection.
  

6. Install the New Headlight Assembly: Position the new headlight assembly into place. Be careful not to pinch any wires. Start inserting any screws/bolts by hand to avoid cross-threading. If it’s a tight fit, don’t force. Check that nothing is obstructing (like a harness caught behind it). Once lined up, tighten the mounting screws or bolts securely. For metal bolts going into plastic housing, don’t over-tighten and crack the plastic. Snug is usually enough. If the assembly uses self-tapping screws into fiberglass or plastic, you might consider using the old holes and not over-torquing to maintain grip.

7. Reconnect the Wiring: Plug the truck’s wiring harness into the new headlight. It should click and lock. For multi-connector setups, ensure each connector goes to the correct component (high beam, low beam, turn signal, etc.). They are usually keyed so you can’t mix them up. If your upgrade requires an adapter harness, connect that chain now (truck harness -> adapter -> new headlight). Secure any loose wiring with zip ties so it won’t dangle or rub on sharp edges.

8. Test the New Headlights: Before buttoning everything up, test the functionality. Turn on the truck’s headlight switch (you can just turn ignition to accessory if you disconnected batteries earlier). Check low beams and high beams. Verify both sides illuminate correctly and that high/low beam functions are on the proper filaments or LEDs. Also activate the turn signals/hazard lights if your assembly includes those, to ensure they flash properly (and at the correct speed, because if an LED turn signal hyper-flashes, you may need a resistor). If anything is not working, stop and troubleshoot now . It’s easier to fix wiring issues with the assembly accessible than after you put all trim back on. Common issues might be a loose connector, a pin pushed out of a connector, or a blown fuse if something shorted. (Replace any blown fuse before proceeding, and rectify any wiring fault if a fuse blew during the install.)

9. Aiming Adjustment (Preliminary): If the headlight assembly has built-in aiming screws (most do), do a preliminary aim adjustment. You can eyeball it for now. For example, the headlight should appear level and pointing straight forward in the housing, not obviously too high or low. We will cover precise aiming in the next section, but it’s good to ensure it’s roughly aligned to avoid blinding oncoming traffic on your way to an aiming test. Typically, turning the vertical adjuster screw will raise or lower the beam. Set it to about where the old one was (if you counted screw turns during removal or marked the wall with old beam, use that as reference).

10. Reinstall Bezels/Trim and Close Up: Once satisfied, reattach any bezels, trim rings, or covers. This might include the chrome ring around a 379’s sealed beams, or the outer bezel on a 579 (make sure it snaps in fully). Replace any rubber seals or gaskets to keep water out of the headlight housing. Finally, close the hood gently and ensure it doesn’t interfere with the new headlights (clearances are usually fine with OEM-fit parts, but double-check that any wiring is not getting pinched by the hood).

11. Final Functional Check: Do one more test with everything assembled: low beam, high beam, turn signals, marker lights. Take a walk around the front of the truck and ensure both sides look symmetrical in brightness and alignment. If one side is noticeably higher or brighter, you may need to adjust aim or check that the correct bulb is in place.

12. Clean Up: Dispose of the old bulbs or assemblies properly (note: HID bulbs require special disposal, and halogen bulbs should not be tossed where they can be stepped on as they can shatter). Clean your tools and store them. Now you’re ready to properly aim the headlights, which we’ll cover next.

Replacing headlights can seem intimidating, but by following these steps methodically, even a novice mechanic can successfully install a new Peterbilt headlight assembly. If you run into specific issues (like a stubborn rusted bolt or an electrical gremlin), don’t hesitate to reach out to a mechanic or consult forums for model-specific tips. For example, some Peterbilt owners on forums suggest spraying penetrating oil on 389 headlight pod bolts ahead of time if they’re corroded, to make removal easier. Little tips like that can save a lot of frustration.

With the new headlights installed, you’ve upgraded your Peterbilt’s lighting. Now it’s crucial to ensure those lights are aimed correctly for optimal performance.

Headlight Aiming and Alignment Instructions

Even the best headlight upgrade won’t do much good if the beams aren’t pointed where they should be. Proper headlight alignment ensures you get maximum visibility while avoiding glare to other drivers. Big rigs like Peterbilts sit taller than cars, so aiming is especially important. A misaligned truck headlight can easily blind oncoming traffic or waste light into the trees or road directly in front of you. Thankfully, aiming your Peterbilt’s headlights is straightforward with a flat wall and a little patience.

When to Aim: It’s wise to check headlight alignment whenever you install new headlights or bulbs, and periodically as part of maintenance. Factors like suspension sag, heavy loads, or wear can shift your aim over time. If drivers flash their high beams at you often (when you’re on low beam), that’s a clue your lights might be aimed too high. Or if you notice you overdrive your headlights (not seeing far enough), they might be too low.

Follow these steps to aim your headlights properly (this applies to most Peterbilt models, but some have specific instructions in the manual):

Tape cross marks on a wall to align headlight beams (Illustration of headlight aiming setup)

1. Find a Level Spot and Wall: Park the truck on a level surface facing a flat wall or garage door. Ideally, you want about 25 feet of distance from the wall to the truck’s headlights. A paved parking lot or driveway works well. Ensure the truck is unloaded (or at typical load) and tires are inflated properly. Ride height affects aim. It’s best to do this at dusk or night for easier visibility of the beam pattern.
   
2. Mark Headlight Centerlines: Turn on low-beam headlights and drive up close (within a few feet) to the wall. From inside the cab, level the steering wheel (truck pointing straight at the wall). Now go in front of the truck and use masking tape to mark the wall at the center of each headlight beam’s hot spot. Typically, you’ll see a bright patch. Mark its center horizontally and vertically with tape, making a cross or plus “+” shape. Do this for both left and right lights. These crosses represent where your headlights hit the wall at zero distance. Double-check that the crosses are at the same height from the ground. If not, your truck might be on uneven ground or suspension leaning. (If one side is slightly lower due to equipment or fuel weight, that’s okay, you can use the average height.) These tape crosses should correspond to the headlight bulb centers.
   
3. Back Up 25 Feet: Now, back the truck straight backwards until the headlights are 25 feet from the wall (measure from the headlight lens to the wall). It helps to mark 25’ on the ground with tape as well, so you know where to stop. Leave the headlights on low beam.
   
4. Observe the Beam on the Wall: Each headlight beam will project a pattern on the wall. For DOT-regulated low beams, the pattern typically has a distinct horizontal cutoff line with a “kick up” toward the right (passenger side). At 25 feet, you want the brightest part of the beam to drop slightly below the height of the tape cross:
   
   • Vertical Aim: The top of the low-beam cutoff (horizontal line) should be about 1 to 2 inches below the level of the headlight center height marked by your tape. In other words, the beam should have dropped an inch or two over 25 feet. This slight downward angle prevents glare at long distance but still gives good forward visibility. For trucks with very high headlight height (e.g., a lifted suspension), aim for closer to 2″ drop. For lower lights, ~1″ drop might suffice. If your beams have no sharp cutoff (older sealed beams), use the top of the main bright spot as reference.
     
   • Horizontal Aim: The bright spots or “center” of each beam should line up with the vertical tape lines you made, or slightly to the right on the passenger side. Typically, the driver’s side low beam is aimed directly straight or a hair to the right, and the passenger side can point a bit further right (to illuminate the shoulder/ditch). A good rule: the left headlight beam’s center should hit just to the right of the left tape cross (so it doesn’t blind oncoming traffic), while the right headlight can align with the right tape cross. Both beams should be level with each other horizontally (i.e. one shouldn’t be higher than the other on the wall).
     
5. Adjust the Headlight Aim: Use the adjustment screws on the headlight assemblies to move the beams. Most Peterbilt headlights have two adjusters per lamp. One is for vertical (up/down) and one for horizontal (left/right). They might be labeled “U-D” and “L-R” or have arrows. On sealed beam setups, these are often Phillips or hex screws accessible from the front with the bezel off. On composite headlights, you might find the adjusters sticking out behind the assembly (sometimes requiring a screwdriver inserted through a hole).
   
   • To lower the beam, turn the vertical adjuster in the direction that moves the hotspot down. Typically, turning the screw clockwise (when facing the screw) will move the beam down on many designs, but this can vary.
     
   • Adjust each side’s vertical aim so the cutoff or hotspot aligns ~1–2″ below the original height mark. Use a tape measure on the wall if needed to get it right.
     
   • If horizontal adjustment is needed, turn the horizontal screw to center the beam with the tape cross vertically. The beams should be pointing straight ahead or just slightly inward (some recommend a slight inward toe so beams converge at a point ahead, but generally with large trucks you keep them almost parallel or very slightly toe-in). If your right beam is way off to the side (for instance after replacing an assembly, it might start off crooked), bring it in line with the mark.
     
6. Check Alignment and Pattern: Once adjusted, step back and look at the wall pattern with both low beams on. Both cutoff lines should be at the same height and relatively flat. The left beam’s cutoff might appear a tad lower. That’s okay if you’re intentionally trying to reduce glare. The overall illumination should look symmetrical. If you have a helper, have them sit in the cab with weight on the driver’s seat and see if that changes aim slightly (probably minimal). Also, if you usually haul a loaded trailer at night, consider that a heavy trailer can squat the rear and raise your headlights. In such cases you might aim a hair lower to account for that.
   
7. Test High Beams: Now test the high beams. High beams typically don’t have a cutoff; they shine straight. At 25 feet, high beams will appear as bright circles on the wall higher than the low beams. There’s usually not much adjusting specifically for highs (they move with the lows in most two-filament designs). But ensure they are roughly centered and overlapping. You don’t want cross-eyed high beams. If your low beams are correctly aimed, the highs should also be fine. Some Peterbilts (with separate high beam units) might allow slight independent adjustment; refer to manual if so.
   
8. Road Test: Finally, take the truck out at night for a road test. Preferably find a low-traffic road. Observe the throw of the low beams. You should have a clear view of the road ahead without needing auxiliary lights. Road signs on the right should light up, but you shouldn’t be excessively lighting oncoming lanes. If oncoming drivers are still flashing you, you may need to tweak the aim a bit lower. Also ensure you have enough forward distance. The low beams should light up at least ~350–500 feet ahead on flat ground. High beams, of course, will go even farther.
   

Proper alignment as described ensures optimal lighting: you’ll see far down the road (critical at highway speeds for stopping distance) and also illuminate the right-side shoulder (important for spotting wildlife, pedestrians, etc.), without blinding oncoming drivers. Remember that in the U.S., low beams are asymmetrically designed to direct light slightly downward-right. This is why aiming charts call for that slight drop and rightward bias. It’s both safer and actually required by law (headlights must meet certain height and aim specs per state and federal regulations).

One extra tip: If your Peterbilt is frequently driven by different drivers or has front suspension adjustments, re-check the aim periodically. Also, after any front-end work (like suspension or if you hit a large bump/pothole hard), the aim could shift. A quick wall check takes only a few minutes and ensures your expensive headlight upgrade is delivering the performance (and safety) you paid for.

By taking the time to align your headlights, you maximize your night visibility and ensure compliance with regulations. In short, aiming your headlights is just as important as installing them. Enjoy the confidence of driving with properly aimed, bright lights. It reduces fatigue and makes nighttime trucking much safer.

Troubleshooting and Maintenance Tips

Upgraded headlights can greatly improve your driving experience, but it’s important to maintain them and address any issues that arise. Here are some troubleshooting and maintenance tips for Peterbilt headlight assemblies:

• Condensation or Moisture in Headlight: It’s not uncommon, especially in humid or rainy climates, to find fog or droplets inside a headlight lens. While most modern assemblies have a vent to equalize pressure, seals can fail. If you see moisture:
  
  • Remove the assembly (if easy) and dry it out. You can use a hairdryer or gently bake the headlight in a warm oven (around 150°F) for a short time to evaporate moisture. Use caution with this!.
    
  • Inspect for cracks or seal failures. Reseal any gaskets or apply a thin bead of silicone around lens edges if you suspect leaks.
    
  • You can place a small silica gel packet inside the housing (away from bulbs) to absorb moisture as a temporary fix.
    
  • Long term, if condensation keeps returning, the unit might need replacement. Persistent moisture can corrode bulbs or LEDs and reduce light output.
    
• Headlight Flickering (LED Upgrades): If you installed LED bulbs or assemblies and notice flickering or strobing, especially at low voltage or when the engine is off, this could be due to the truck’s electrical system PWM or CAN-bus sensing:
  
  • Install anti-flicker harnesses or resistors if not already. These stabilize the current to the LED and add load to mimic a halogen bulb, stopping minor flicker.
    
  • Check all ground connections. A loose ground wire can cause intermittent power loss leading to flicker. Ensure the headlight ground strap or wire is securely bolted to clean metal.
    
  • Verify that the truck’s alternator and batteries are in good shape. Large voltage swings in the system can show up as flicker in sensitive LED electronics.
    
  • If the truck uses the headlights as daytime running lights (DRL) at reduced voltage, some LED kits will flicker at the lower voltage. In that case, a DRL module or adapter may be needed (some LEDs are not compatible with reduced-voltage DRL by default).
    
• One Headlight Out or Dim: If a headlight isn’t coming on:
  
  • First, try the simple things: Is there a burnt bulb (for halogen)? Replace it. For LEDs, check any inline fuse or swap the left/right units to see if the problem follows the unit or stays on the truck side.
    
  • Check the fuse for that headlight circuit. Peterbilts often have separate fuses for left and right low beams (and separate for high beams). A blown fuse could point to a short.
    
  • Inspect the wiring harness and connector for damage or corrosion. A common issue in older trucks is the headlight connector melting or corroding, causing an open circuit or high resistance (dim light). In such cases, installing a new pigtail connector is the fix.
    
  • If the headlight is dim yellow while the other is bright white (assuming same type bulb), that’s a sign of a bad ground connection on the dim side. The bulb may be backfeeding through other circuits. Clean and tighten the ground point for that headlamp.
    
  • For sealed beam setups: ensure the terminals on the back of the sealed beam aren’t corroded. Sometimes removing and replugging the connector a few times can rub off minor corrosion.
    
• Beam Pattern Issues: After an upgrade, you might notice the beam pattern isn’t right (e.g., strange shadows, or too much scatter/glare):
  
  • Double-check the bulb seating or orientation. Many LED/HID retrofits need to be oriented correctly (LED chips at 3 and 9 o’clock position typically) to emulate the filament position. If an LED bulb isn’t locked in correctly, the beam pattern will suffer.
    
  • Ensure any shields or cutoffs in the assembly were reinstalled if you moved them. Some projector retrofits have a cutoff shield that can be accidentally left out.
    
  • If using HID in a reflector not meant for it, be aware that you may never get a great pattern. Consider switching to a proper projector or an LED solution designed for that housing to get a clean cutoff.
    
• Cleaning and Restoring Lenses: Over time, polycarbonate headlight lenses can get cloudy or yellow due to UV exposure (especially on 579, 387, 330, etc., with large plastic lenses). This reduces light output.
  
  • Use a headlight restoration kit to polish and clear up the lenses. This usually involves wet sanding with fine grit, then polishing compound, and applying a UV protectant clear coat. It can make a dramatic difference in brightness.
    
  • For severe cases, you might replace the lens or the whole assembly if restoration isn’t satisfactory. Keeping lenses clear is key to maintaining brightness.
    
  • To prolong clarity, consider applying a film or UV sealant to the lenses after restoring, and park trucks facing away from direct sun when possible.
    
• Vibration and Loose Mounts: Trucks endure a lot of vibration, which can loosen headlight mounting over time:
  
  • If you notice a headlight beam shaking while driving, inspect the mounting bolts and adjusters. A broken plastic adjuster or loose screw can cause the light to jiggle. Replace any broken adjuster (they are often cheap nylon pieces. Many truck part shops sell headlight adjuster repair kits).
    
  • Adding a lock washer or a dab of threadlocker (Loctite blue) on mounting screws can help them stay tight against vibration, but use sparingly and avoid on adjuster screws (you still want to be able to turn those).
    
  • Make sure any rubber cushion or grommet that is meant to support the headlight assembly is in place. Some models have small rubber pads to reduce vibration.
    
• Upgrading Alternator/Batteries (for Extensive Lighting): If you’ve significantly upgraded to power-hungry lights (like added a bunch of auxiliary driving lights or older HID ballasts), ensure your electrical system can handle it. LEDs generally use less power than halogens, so they aren’t a strain. For example, replacing four 65W sealed beams with four 25W LED units actually cuts power draw by more than half. But if you added lighting, monitor your battery voltage. Most Peterbilts have heavy-duty alternators, but it’s worth checking that with all lights on, the system stays at ~14 volts. Dim lights at idle might indicate you need a higher output alternator or an extra battery for heavy accessory loads.
  
• Spare Bulbs and Parts: Keep a set of spare bulbs in the truck (if you still use halogens). This is a simple tip, but critical for fleet operations. A spare H4 or 9007 bulb in the glove box can save you from a ticket or from having to drive with one headlight until you find a parts store. If you’ve upgraded to LEDs, quality ones rarely fail spontaneously, but it could happen. Carrying one of your old halogen bulbs as a temporary backup could be worthwhile on long trips (since an LED driver failure could otherwise leave you dark). Some owner-operators even carry a spare headlight assembly if heading to remote areas, though that might be overkill unless you have a known issue.
  
• Regular Inspection: During your pre-trip inspections, include a quick headlight check. This means not just seeing if they turn on, but also looking for:
  
  • Cloudiness or haze on the lens.
    
  • Water inside the lamp.
    
  • Cracks or stone chips (a big crack can let water in or cause the bulb to fail).
    
  • Secure mounting (give the lamp a gentle shake to make sure it doesn’t wobble).
    
  • Proper aim (you can tell if one’s drastically high or low by the pattern on the ground in front when you’re close to a wall).
    
  • Also verify all auxiliary front lights (marker, turn signals in the headlight housing, fog lights if equipped) are working, since those often share grounds or feeds with headlights.
    
• Legal Considerations: Ensure any headlight modifications remain DOT legal. This means:
  
  • The assemblies should have “DOT” or SAE markings if they are replacements. This indicates they meet beam pattern and brightness regulations. If pulled over or during inspection, an officer might question unmarked lights.
    
  • Avoid colored lights (beyond the allowed white or selective yellow). Blue or purple tints are illegal in most jurisdictions.
    
  • If you added an LED light bar or extra driving lights, make sure they’re wired to a separate switch and off for on-road use (and covered if required by law).
    
  • Keep headlights clear of obstructions. Don’t put bug screens or chrome covers that significantly alter light output. Some dress-up headlight covers are not legal on highways at night.
    

With these troubleshooting and maintenance practices, you’ll keep your Peterbilt’s headlights shining bright for the long haul. Remember that a headlight upgrade isn’t a one-and-done deal.  Maintaining them is an ongoing part of truck ownership. The payoff is worth it: you’ll have reliable illumination, fewer problems on the road, and a safer experience for both you and other motorists.

FAQs about Peterbilt Headlight Upgrades

Q1: Are LED headlights legal on Peterbilt trucks?

Answer: Yes, LED headlights are legal for on-road use as long as they are DOT-approved and properly aimed. The DOT and FMCSA regulations don’t forbid LED or HID tech, but they require that headlights meet certain beam pattern and brightness standards (FMVSS 108). So, use LED replacement units that are labeled SAE/DOT compliant. Avoid ultra high-output “off-road only” LEDs or those with colored halos that can be non-compliant. When installed and aimed correctly, LED headlights will pass inspections. In fact many new trucks now come with factory LEDs. During a DOT inspection, officers will mostly check that your headlights function, are not cracked, and aren’t blinding oncoming traffic. So after upgrading, always double-check your alignment. In summary: LED conversions are legal and a great upgrade, provided you choose quality DOT-rated products and adjust them properly.

Q2: What’s the difference in brightness between halogen and LED in real terms?

Answer: It’s significant. A standard halogen bulb (or sealed beam) might emit around 1,200 lumens, whereas an LED replacement can put out 6,000+ lumens. That’s roughly 3-5 times brighter. In practical terms, after upgrading to LEDs, you’ll notice a much wider and longer light beam. Road signs will reflect from farther away, and the light will be a crisp white instead of yellow. For example, a trucker forum member noted that after upgrading a 379 to JW Speaker LED headlights, it was “like night and day”. No more overdriving the headlights at highway speeds. Just be aware that more lumens doesn’t always equal better unless the beam is focused correctly. A well-designed 3,000 lm HID can outperform a cheap 6,000 lm LED if the latter scatters light everywhere. But quality LED kits today generally have excellent beam focus. Bottom line: expect a 300% to 400% increase in effective brightness with a good LED upgrade, resulting in greatly improved night visibility.

Q3: Can I upgrade my older Peterbilt 379 or 359 to LED headlights without modifying the truck’s wiring?

Answer: Yes. In most cases it’s plug-and-play. Older Peterbilts like the 359, 379 (and related models 378, 357) typically used either 4×6″ rectangular sealed beams or 5.75″ round sealed beams. There are direct-fit LED sealed beam units that plug into the same 3-prong connector (H4656/H4666 type for 4×6, or H4 3-prong for 5.75″ rounds). You can literally remove the old halogen sealed beam and plug the LED unit into the existing harness. No rewiring required. The only consideration is that if your truck had daytime running lights or uses the headlight circuit in a weird way, you might need a resistor harness to avoid flicker (not common on those older models, usually only an issue on newer trucks with CAN-bus). Also, physically, you may need to slightly adjust or trim the headlight bucket on some conversions if the LED’s heat sink is bigger, but most are designed to fit. So, for a classic Pete: order a set of DOT-approved LED sealed beams, and it’s typically a straightforward swap in the stock buckets using stock wiring. Always secure the new lights well (most come with adapter rings or fit exactly). Many owners of 70s-90s Petes have done this upgrade and report no electrical issues. In fact, the lower draw of LEDs is gentler on the wiring.

Q4: My new LED headlights cause the turn signals to hyper-flash. How can I fix this?

Answer: This happens because LED turn signals (whether in the headlight assembly or separate) draw much less current than the old incandescent bulbs, so the flasher relay thinks a bulb is out (causing rapid flash). To fix it:

• Install load resistors in parallel to the LED turn signal wires. A 50W 6Ω resistor on each turn signal circuit will simulate the load of a bulb, restoring normal flash speed. These resistors get hot, so mount them on metal away from other wires.
  
• Alternatively, replace the flasher relay with an electronic no-load flasher that is LED-compatible (if your truck uses a 2- or 3-prong flasher unit). Many newer Petes have the flasher controlled by the body control module, so in that case resistors are the way to go.
  
• Some LED units include built-in resistors. If yours didn’t, the external resistor solution is simplest.
  Make sure to attach the resistor leads securely (tap into the turn signal + and ground). Once installed, your turn signals should flash at the normal rate again.
  

Q5: How long do LED headlights really last on a truck?

Answer: Quality LED headlights can last years, even decades. Many are rated at 30,000 to 50,000 hours of operation. For perspective, 50,000 hours is over 5.5 years of continuous 24/7 use! In a truck, if you drove with lights on 8 hours a day, that’s about 17 years. In reality, other factors usually end the LED’s life: extreme heat, vibration, water intrusion, or electronic driver failure. But reputable brands design their LEDs for the rigors of trucking with robust housings, shock-resistant circuits, and cooling fans or heat sinks. We’ve seen fleet customers run the same LED headlights for 5+ years with no noticeable dimming. By contrast, halogen bulbs often burn out annually or biannually. It’s wise to buy LEDs that have a solid warranty (at least 2-3 years), which is a good indicator of expected life. Note: the LED chips may last that long, but if the lens gets cloudy or the housing fails, that can effectively end the useful life too, so maintenance (like keeping the lenses clear and sealed) matters. Overall, expect 10-15 times the lifespan of halogens. Most likely, you’ll retire the truck before the LEDs themselves die.

Q6: What are the best headlight upgrades for maximum visibility when driving off-road or in rural areas?

Answer: Assuming you’ve upgraded to good LEDs or HIDs for your low/high beams already, the next step for maximum visibility is adding auxiliary lighting:

• LED Driving Lights or Light Bars: These can tremendously boost forward lighting. For instance, an LED light bar mounted on the bumper or roof can throw light far down range. Great for rural highways or off-road. Just be sure they’re switched off for oncoming traffic (they’re usually for off-road/use with no traffic). Many Peterbilt owners mount a pair of LED driving lights on the front bumper or add a 20-30″ light bar behind the grille.
  
• Fog Lights: If you run in fog, rain, or snow, a pair of selective yellow fog lights low to the ground can cut through the murk and improve contrast. Mount them in the bumper or tow hook area. They should have a wide, low beam pattern (SAE “Fog” pattern) to illuminate the road directly ahead and sides without glare.
  
• Upgraded High Beams: Some people install slightly higher wattage bulbs in high beams (e.g. a 70W halogen in place of 60W), but with LEDs that’s not applicable. If you still have halogen highs, you could consider a 100W off-road bulb for high beam only (illegal on road though, so use with discretion).
  
• Heated Lens LED Lights: In very cold climates, LED headlights don’t generate much heat on the lens, so they might not melt snow/ice buildup. For maximum visibility in winter, consider heated LED headlights (some brands like Truck-Lite offer them) that electrically keep the lens warm to prevent icing.
  
• Headlight Aimers or Adaptive Lights: A luxury option. Some new trucks have adaptive headlights that swivel in turns, etc. Not really an upgrade you can easily retrofit on an older model. But ensuring your lights are well-aimed (even slightly upward for off-road use) could help.
  In summary, a pair of quality LED driving lamps and good fog lights combined with your upgraded headlights will give you an impressive amount of light. It’s not uncommon for well-equipped rigs to have over 20,000 lumens of combined lighting. Turns night into day on those back roads. Just remember to dip/turn off auxiliary lights around other vehicles to stay legal and courteous.
  

Q7: My Peterbilt has 4 headlight bulbs (2 low, 2 high). Should I upgrade all to LED or just the low beams?

Answer:Ideally, upgrade both low and high beams to LED. Low beams are used the majority of the time, so they’re the priority. You’ll see a huge benefit there. But leaving halogen high beams while low are LED can be a bit disappointing; when you flick to high, the color and intensity change back to halogen dim yellow. Many drivers find that jarring, and actually the LED low beam sometimes illuminates so well that the stock highs add little. So for the best outcome, do them all. Most 4-light systems use either H11/H9 or H7 bulbs, etc. It’s easy to swap all four. If budget is a concern, you could do lows first (for the immediate benefit) and then highs later. Just make sure the color temperature of both sets match if possible (you don’t want one cool white and one warm white). And if you do heavy nighttime highway driving, high beam performance is crucial, so it’s worth it. The good news is LED highs run cooler and last long even if you don’t use them as much, and you won’t have to worry about blown high beam bulbs at inspection time. Bottom line: upgrade everything, or go with an integrated LED assembly that includes both high and low in one unit.

Q8: Do I need to add relays or a heavier wiring harness for higher wattage headlights?

Answer:For LED upgrades, generally no harness upgrade is needed because LEDs draw less current than stock halogens. If anything, they ease the load on your switches and wires. If you were upgrading halogens to significantly higher wattage halogens (say from 60W to 100W bulbs), then yes, a relay harness would be smart to protect the headlight switch and ensure full voltage at the bulbs. Many older trucks benefit from relay harnesses to get brighter halogen output. But with modern LED kits, they often come with their own driver modules and work with the existing wiring. The factory Peterbilt headlight circuit can handle the stock ~10 amps per side (for dual 55W low beams). A pair of LED lows might draw only 2–3 amps, so no stress. Just plug them in. One exception: If you find that the LED lights aren’t getting enough voltage (maybe due to thin OEM wiring or voltage drop), a relay harness could help feed them a solid 14V from the battery. This can eke out a bit more performance. But most quality LED retrofits are designed to work with OEM wiring. So unless you’re doing something exotic, additional relays are not required. It won’t hurt to use them, but it’s usually not a noticeable improvement for LEDs the way it is for halogens.

Upgrade with Confidence (and Our Free Shipping!)

Upgrading and aligning your Peterbilt’s headlights is one of the best investments you can make in safety, compliance, and driver satisfaction. With the information in this guide, truck fleet managers and owner-operators can approach a headlight assembly upgrade with clarity and confidence. We’ve seen why modern LED headlights outperform old halogens, how to choose the right parts for models like the 379, 389, 579, 330, 337, and 367, and the importance of proper installation and aiming. By following the steps and tips above, you’ll achieve brighter, farther-reaching illumination that keeps your rigs running safely through the night.

At PeteTruckParts.com, we are passionate about helping you make these upgrades a reality. Our extensive Headlights Collection features DOT-approved LED and halogen assemblies for all major Peterbilt models, whether you need a factory-style replacement or a cutting-edge upgrade. We stock trusted brands and offer expert advice to ensure compatibility with your specific truck. Don’t forget, we also have a full range of Peterbilt lighting parts. From fog lights and marker lights to wiring harnesses and switches, we are a one-stop shop for all your lighting needs.

Why buy from PeteTruckParts? We offer free shipping on orders over $500, helping fleet customers save on bulk purchases. Our knowledgeable team is just a phone call away. We encourage you to call us to order or if you have any questions about which headlight upgrade is right for your Peterbilt. We pride ourselves on clear, confident, and knowledgeable support, just as we hope this guide has been helpful and informative.

An upgraded and aligned headlight system means your trucks will shine brightly and legally wherever they travel. From busy highways to dark back roads, it’s about safety for your drivers and everyone else on the road. So don’t wait: take action on that headlight upgrade today. Enjoy the improved visibility, the modern look, and the peace of mind that comes with knowing you’ve made a smart, safety-conscious improvement to your truck. Illuminate the road ahead with confidence!

Drive safe, and thanks for choosing PeteTruckParts for your headlight needs.

Additional Resources

• “Headlights: IIHS Research Overview.” Insurance Institute for Highway Safety. Key data: ~50 % of traffic deaths occur in dark or dusk conditions; better headlights reduce nighttime crashes. IIHS 

• 49 CFR § 571.108: Federal Motor Vehicle Safety Standard No. 108: Lamps, Reflective Devices, and Associated Equipment. U.S. Department of Transportation / eCFR. Key data: legal requirements for headlamp performance, construction, and aim. eCFR 

• “Peterbilt 379.” Wikipedia (archival manufacturing specs). Key data: production years 1987 – 2007 for the 379 model line. Wikipedia 

• “Peterbilt Celebrates Production Milestone with 100,000th Model 389.” Peterbilt Motors press release, 7 Sep 2023. Key data: Model 389 was introduced in 2006 (supports model-year reference). Peterbilt

• “Peterbilt New Model 579 Redefines the Look Inside and Out.” Peterbilt Motors press release, 2021. Key data: aerodynamic 579 launched in 2012, with later LED options. Peterbilt

• “Car Headlight Lumens Guide: Halogen vs LED vs HID.” CarLightVision tech blog, 2025. Key data: typical lumen output (halogen ≈ 1,200 lm, LED ≈ 6,000 + lm) Carlightvision

• “LED Headlights: 5 Key Factors That Affect Lifespan.” CarLightVision tech blog, 2025. Key data: average LED headlamp life 30,000 – 50,000 hours vs halogen ≈ 1,000 hours. Carlightvision

• “Heated LED Headlamps.” Truck-Lite product information page, 2025. Key data: availability of self-heating LED lamps for ice-prevention in cold climates. truck-lite.com

• “Headlamp Aiming Chart.” Utah Department of Public Safety (PDF), 2019. Key data: industry-standard 25-ft wall-aiming method and allowable beam tolerance. https://site.utah.gov

• NHTSA Service Bulletin: Headlamp Aiming Check & Adjustment (25 ft method). National Highway Traffic Safety Administration, 2020. Key data: federal guidance confirming 25-ft distance for aim verification. static.nhtsa.gov