What You're Actually Buying
This is a cosmetic/protective cover, not the whole mirror arm - it snaps or bolts over the 78606-509 arm assembly on the passenger side. If your cover is cracked, faded out, or missing altogether (common after a mirror gets clipped), this is the piece that fixes it without replacing the whole arm.
Freightliner used this arm/cover combo across a wide run of Cascadia production, so you'll see it on trucks that otherwise look pretty different trim-wise. The cover itself is a bolt-on/snap-fit item - no wiring, no glass, no adjustment motor involved.
Why These Numbers Cross
The 2278606509 and 78606-509 references you see in the cross-list are the mirror arm assembly this cover was designed to fit - not a different cover part number, just the parent assembly. That's why you'll find the cover number and the arm number tangled together in catalogs; they're sold as a system even though you can buy the cover separately.
563.46104C and FRCA-1401-2-RS32 are the aftermarket manufacturer's own part numbers for the same physical cover. Different suppliers stamp their own numbers on the box, but the tooling traces back to fitting the same 78606-509 arm.
Watch the obvious stuff: RH vs LH (this is passenger side only), and confirm you actually have the 509-series arm underneath. Freightliner changed arm designs over the Cascadia's run, so a cover that fits a later arm won't snap onto an earlier one even if the truck badge says Cascadia both times.
Ordering From Us
We keep this one in stock at the Tacoma counter - if you're local, same-day pickup is normal. If you're not local, it ships nationwide and usually gets to a shop or terminal in a couple days.
Comes with our standard 6+ month warranty. If it doesn't snap on right or the fitment's off, we want it back - not sitting on a shelf as a return excuse.
Before you order: pull the number off your old arm or cover, or give us the truck's VIN. Cascadia mirror hardware has enough variation across model years that a five-minute check beats a mismatched part sitting in a box.
22-78606-518 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 22-78606-518. 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 |
|---|---|
| OE/Cross-Ref | 563.46104C, FRCA-1401-2-RS32, 2278606509 |
| Cross-Reference | 78606-509, 78606-518 |
Frequently asked questions
Does 22-78606-518 fit my 2015 Cascadia?
Depends which arm assembly your truck has - Freightliner ran more than one mirror arm design across Cascadia production. Check the number stamped on your current arm or cover, or send us the VIN, before you order.
Is this the same as the FRCA-1401-2-RS32 cover?
Same physical part, different manufacturer stamp. FRCA-1401-2-RS32 is another aftermarket supplier's number for a cover built to fit the same 78606-509 arm. Confirm your old part's number matches up before assuming interchange.
Can I just replace the cover, or do I need the whole mirror arm?
If the arm itself isn't bent or cracked, the cover alone does the job - it's a separate snap-on piece. No need to buy the full 78606-509 assembly unless the arm's actually damaged.
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.