What This Belt Is and Where It Goes
This is a Micro-V (multi-ribbed) serpentine belt, not a V-belt, so it's got the fine ribbed grooves that mate to a specific pulley profile. On the Volvo VT 2006-2010 it's the single belt that drives everything hanging off the front of the engine - alternator, AC compressor, power steering, sometimes the fan depending on how the truck's spec'd.
Length and rib count matter more than most guys think. Get it wrong by even one rib or a few inches of length and you'll either not get it on the pulleys or it'll run loose and slap around under load. That's why we stick to the Volvo number and its direct crosses instead of guessing off a tape measure.
Numbers 21189554, 23961883, 3811958, and GT-4120842 all reference this same belt across different catalogs and supersession updates Volvo's run over the years. Different part number doesn't mean different belt - it usually means a different year the number got printed in a parts book.
How the Cross-Reference Numbers Line Up
The headline number 03-20 shows up in some catalogs as a mfr code alongside the Volvo numbers - same belt, different indexing. ACDelco's 12K842, NAPA's 25-120842, Cummins 3100402, and Navistar 4120384C1 are the aftermarket and OE-adjacent numbers that cross to this same rib pattern and length for the VT chassis.
Where guys get burned on serpentine belts isn't usually the belt itself, it's the tensioner arm underneath. If your tensioner pulley is worn or the arm doesn't have travel left, a brand new belt will still squeal or wear fast. Check the tensioner and idler pulleys while you've got the old belt off - saves you a comeback in three weeks.
Surest way to confirm before you order: pull the old belt and read the number off the backside, or better yet, run your VIN. Belt specs can shift depending on whether the truck's got AC, what alternator size is on it, and a few other options that changed mid-run on these trucks.
Ordering From PartStop
We keep 20481362 in stock at the Tacoma counter for guys who need it same-day - walk in, walk out, back on the road. If you're not local we ship these nationwide and they move fast since it's a common failure item on the VT.
Comes with our standard 6+ month warranty. If it's the wrong belt for your application we'll sort it, but confirm the number off your old belt or your VIN before you order so we get it right the first time.
This is an aftermarket belt, direct replacement for the numbers listed - it interchanges with the Volvo, ACDelco, NAPA, Cummins, and Navistar numbers above, but always double check against what's coming off your truck.
03-20 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 03-20. 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 | 12K842 |
| NAPA | 25-120842 |
| Cummins | 3100402 |
| Navistar | 4120384C1 |
Frequently asked questions
Does 20481362 fit my 2008 Volvo VT with the Cummins ISX?
Likely yes, but confirm off the old belt or your VIN first - accessory spec (AC, alternator size) can change the belt length even within the same model year, so don't order off year alone.
Is this the same belt as NAPA 25-120842?
Yes, that's a direct cross-reference for the same rib pattern and length. Different box, same belt - but if you've got the NAPA number off the old part, that confirms you're ordering the right one.
My old belt has a different number stamped on it than any of these - what do I do?
Bring it in or send us a photo of the number. Volvo's run a few supersessions on this belt over the years and we can usually match it up, but don't guess off a partial 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.