What This Belt Actually Runs
This is the main drive belt off the crank pulley that spins your alternator, AC compressor, water pump, and power steering pump on the ISX. If it lets go, you lose all of that at once — not just one system. That's why guys notice it fast when it's cracked or glazed.
10PK1275 tells you the specs: 10 ribs, 1275mm effective length. That's the number stamped on most of these belts regardless of brand, and it's the fastest way to confirm you're looking at the right part before you order.
Freightliner's own parts number for this application is 01-35605-275, which is just their private-label version of the same Gates/Dayco belt. Same belt, different box.
Why All These Numbers Cross to Each Other
Gates K100502 and 4100502DF, Dayco 503K10 and 5100503, ACDelco 10K502, NAPA 25-100502 — these all cross because they're built to the same rib count, length, and profile spec. Belt manufacturers don't reinvent this stuff; they build to the OEM's engineering print, so cross-referencing is normal and reliable as long as the numbers match on rib count and length.
Where guys get burned is grabbing a belt that's close but not exact — a 1270mm or 1280mm length instead of 1275mm. It'll go on, run for a while, then start slipping or throwing itself off the pulley under load. Bando's 10PK1280 is a good example — close enough to install, wrong enough to cause comebacks.
Rule of thumb: pull the old belt off the truck and read the number stamped on the backside. That's your source of truth, not what a catalog thinks fits your model year. Cascadia spec changed enough over those years that VIN alone won't always tell you which belt length you need.
Ordering From Us
We keep K100502 in stock at the Tacoma counter for walk-in and will-call, so if you're broke down local we can usually get you a belt same day. For fleets outside the area we ship nationwide and can get it out same-day if you order before cutoff.
Every belt we sell carries our 6+ month warranty. If something's off with fit or the belt fails outside of normal wear, bring it back or call us — we'll sort it.
If you're not 100% sure which belt your ISX takes, snap a photo of the old belt's stamped number or give us your VIN and we'll confirm before it ships. Cheaper than guessing and having it come back.
0124894004 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 0124894004. 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 |
|---|---|
| ACDelco | 10K502, K100502HD |
| Continental | 503K10MK |
| Dayco | 503K10, 5100503 |
| Bando | 10PK1280 |
| Continental/Goodyear | 4100503 |
| NAPA | 25-100502HD, 25-100502 |
| Continental ContiTech | 4100503X |
| Gates | K100502, 4100502DF |
| Freightliner (OEM) | 01-35605-275 |
Frequently asked questions
Does K100502 fit my 2011 Cascadia with the ISX?
Likely, but confirm it. The ISX front end drive spec didn't change every year, but Freightliner did run more than one belt length across the Cascadia lineup depending on options and accessory setup. Check the number stamped on your old belt or give us the VIN and we'll verify before you order.
Is this the same as the Dayco 503K10?
Yes — same 10-rib, 1275mm belt, just Dayco's part number instead of Gates'. They cross because they're built to the same length and rib spec. Confirm by matching the numbers stamped on your old belt just to be safe.
What's the difference between K100502 and the Bando 10PK1280?
Five millimeters in length — doesn't sound like much, but it's enough to cause premature wear or belt walk-off under load. If your old belt reads 1275mm, stick with that spec. Don't substitute based on a catalog cross-reference alone without checking the actual number.
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.