What You're Getting
This is the complete LH headlight assembly with LED lighting elements for the Freightliner Cascadia body style, 2018 through 2024. Freightliner ran this same headlight design across those model years with only minor internal changes, so the housing shape and mounting points stayed consistent.
It's a driver's side unit — passenger side is a different part number, don't mix them up. Comes with the LED elements already in place, connector pigtail matches factory harness, so no splicing needed on a straight swap.
How the Cross Numbers Line Up
A6601405002 is the Freightliner number you'll usually find on the parts invoice or stamped near the connector. United Pacific makes an aftermarket version of this same housing under UP-35737 (also just listed as 35737 in some catalogs) — same fit, same mounting, built to slot into the same holes as the Freightliner piece.
You'll also see A66-01405-004 floating around — that's an older Freightliner numbering format for what's now A6601405002. Superseded part numbers happen a lot with Daimler/Freightliner as they update production runs, so don't panic if your old part has a different-looking number that still starts with A66-01405.
Headlights are pretty forgiving on interchange compared to something like a hub or brake chamber — there's no spline count or arm length to worry about here. The real gotcha is passenger vs driver side, and whether your truck has the LED or halogen variant. Pull the number off your old headlight or check your VIN before ordering.
Ordering From PartStop
We're in Tacoma and keep these in stock for same-day pickup or will/call if you're running through the Puget Sound area. Ship nationwide too if you're not local — most orders go out same day if you call before early afternoon.
Backed by our standard 6+ month warranty. If it doesn't match up to your old housing, we'll sort it — just don't cut the harness connector until you've confirmed fit.
A6601405002 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to A6601405002. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| United Pacific | UP-35737, 35737 |
| Freightliner (OEM) | A66-01405-004 |
Frequently asked questions
Does A6601405002 fit my 2019 Cascadia?
Most likely, since this number covers 2018-2024 Cascadias, but confirm by checking the number on your existing headlight housing or running your VIN. Freightliner made small changes mid-run on some trims.
Is this the same as the United Pacific 35737?
Yes, UP-35737 is United Pacific's aftermarket version of this same headlight — same mounting and fitment as the Freightliner A6601405002. It's not a Freightliner-branded part, it's a cross-reference aftermarket build.
How do I know if I need the LED or halogen version?
Look at your old headlight — LED units have distinct light bars/projectors versus a single bulb reflector setup for halogen. When in doubt, give us the VIN and we'll match it up before you order.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.