Kenworth T680 Headlight Replacement: Complete Aftermarket Buying Guide (2026)

Last updated: May 2026 · 7 min read

The Kenworth T680 is one of North America's most popular Class 8 highway tractors, with hundreds of thousands on the road. When the headlight fails — and they do, especially the inboard turn signal LED clusters — Kenworth dealership pricing is brutal: $850-$1,400 per assembly. Quality aftermarket alternatives run $200-$450, with the same DOT-approved fitment.

This guide explains exactly what to look for when buying an aftermarket T680 headlight, how to verify the right fitment for your year, and the OEM cross-reference numbers you need to confirm the aftermarket supplier has the correct part.

T680 headlight types by year

Kenworth changed the T680 headlight design three times between 2014 and 2025:

• 2014-2018 first-gen T680 — Halogen low/high beam with separate LED daytime running light strip
• 2019-2021 T680 Next Gen (early) — Full LED with redesigned bezel and integrated turn signal
• 2022-2025 T680 Next Gen (refresh) — Updated LED with revised mounting tabs (parts NOT interchangeable with 2019-2021)

Critical: aftermarket headlights are year-specific. A 2017 T680 headlight will NOT fit a 2020 T680 even though both are "T680." Verify your truck's exact build year before ordering.

OEM Kenworth T680 headlight part numbers

Use these to verify your aftermarket supplier has the correct cross-reference:

Quality aftermarket suppliers list these cross-references in their product descriptions. If the supplier doesn't list them, they may not have the right part.

What to look for in an aftermarket T680 headlight

1. DOT and SAE compliance markings — Required for road-legal use
2. Polycarbonate (not glass) lens — More impact-resistant on highway debris
3. Sealed housing with integrated weather seal — Prevents moisture intrusion (the #1 failure mode for T680 headlights)
4. Direct-fit mounting tabs — Should bolt to OEM mounting points without modification
5. 1-year warranty or longer — Anything shorter signals lower-tier quality
6. Cross-reference numbers listed — As shown above

Pricing reality: aftermarket vs Kenworth dealer

Installation tips

T680 headlight replacement is a 30-45 minute job for most users with basic mechanical experience:

1. Disconnect battery (yes, actually do this — there's high-current LED circuitry)
2. Remove the front grille (usually 4-6 push-pin clips)
3. Disconnect the electrical harness from the existing headlight (typically a 6-pin or 8-pin connector)
4. Remove the 4 mounting bolts (10mm or 13mm depending on year)
5. Pull the old assembly forward and out
6. Install the aftermarket assembly using the same mounting holes
7. Reconnect the harness — pin layout should be identical to OEM if you bought a quality part
8. Reinstall grille
9. Reconnect battery and test all functions: low beam, high beam, daytime running, turn signal

Common installation issues to watch for

• Wiring connector doesn't match — Quality aftermarket parts will match the OEM connector pinout. If yours doesn't, you bought a part for a different year.
• Headlight aim is off — All headlights need vertical aim adjustment after install. Use the adjustment screws on the back of the housing.
• One side works, other doesn't — Likely a wiring connector issue, not a defective headlight. Inspect the harness connector for corrosion.
• Daytime running lights don't work — Check the dedicated DRL fuse. Aftermarket parts use the same fuse circuit as OEM.

Frequently Asked Questions

Are aftermarket Kenworth T680 headlights as bright as OEM?

Quality aftermarket T680 headlights match OEM lumen output specifications. LED versions of aftermarket T680 headlights typically produce 4,000-5,500 lumens per side, equivalent to OEM LED ratings. Cheap aftermarket parts may underperform.

Will an aftermarket T680 headlight pass DOT inspection?

Yes, as long as it carries the DOT marking and is properly aimed. Quality aftermarket T680 headlights meet FMVSS 108 standards required for DOT inspection.

Can I upgrade from halogen to LED on a 2014-2018 T680?

Yes. Aftermarket LED conversion headlights are available for the 2014-2018 first-gen T680. They use the same mounting points and OEM electrical connector. The brightness improvement is significant. Cost is typically $350-$500 per side.

What's the difference between SAE and DOT approval?

SAE (Society of Automotive Engineers) sets the technical standard. DOT (US Department of Transportation) is the regulatory approval. A part with both markings has been tested to SAE standards and approved for road use in the US.

How do I know if my T680 has halogen or LED OEM headlights?

2014-2018 came with halogen plus LED daytime running light strip. 2019+ Next Gen came with full LED. If your existing headlights have visible bulbs through the lens, you have halogen. If the lens is uniformly illuminated, you have LED.

Can both Driver and Passenger side use the same headlight?

No. Driver (LH) and Passenger (RH) T680 headlights are mirror-image designs and NOT interchangeable. Always order by side.

Bottom line

The Kenworth T680 headlight is one of the highest-savings aftermarket purchases you can make: $640-$970 per side over OEM dealership pricing, with no functional compromise when buying from a quality supplier. Verify your year, choose a supplier that lists the OEM cross-reference numbers, and you'll get a 30-minute install that pays for itself the first time.