What You're Looking At
This is a heavy-duty 8-rib accessory drive belt, 81 inches around, the kind that runs your alternator, water pump, AC compressor and power steering pump off one continuous loop. Common on Class 8 trucks with Cummins, Detroit and Cat setups where the front-end accessory drive calls for an 8-groove belt at this length.
Belt number 4940003 is our house number for it. GT4080811DF, 3933357, 202952, 5080810 and 8K81 are all the same physical belt under different suppliers' part systems - Gates, Cummins, Dayco and a few others have all had their hand in numbering this thing over the years.
Why All These Numbers Match
Serpentine belts cross a lot cleaner than most parts because there's really only two things that matter: rib count and belt length. This one's 8 ribs, 2058mm (81") - match both those specs and the belt fits the pulley layout regardless of whose sticker is on it. That's why Gates 4080811DF and Alliance N01 8K810 both land on this same belt.
Where guys get burned is grabbing a belt that's close but not exact - a 2060mm or a 7-rib on an 8-rib pulley setup. It'll look right hanging on the shelf and then either squeal, throw itself off the pulley, or just wear the ribs down early. Length and rib count both have to nail it, no slack.
Surest way to confirm before you order: pull the old belt and read the number stamped on the backside, or check the belt routing diagram under the hood/on the fan shroud. If it's worn past reading, measure rib count and full loop length with a tape - that's usually enough to nail it down.
Ordering From PartStop
We keep this one in stock at the Tacoma counter - if you're local, it's a same-day grab, no waiting on freight. Ship nationwide too if you're not close enough to walk in.
Belt's $29 and comes with our standard 6+ month warranty. It's an aftermarket belt, direct replacement for the numbers listed - not claiming it's a factory Cummins or Gates part, just built to the same spec and rib/length that those parts call for.
If you're not 100% sure this is your belt, call the counter with your VIN or the number off the old belt before you buy. Cheaper than guessing wrong and driving back.
8PK2058 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 8PK2058. 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 |
|---|---|
| Alliance | N01 8K810 |
| Gates | 4080811DF |
Frequently asked questions
Does 8PK2058 fit my Freightliner with a Cummins ISX?
Depends on your accessory drive setup - some ISX configs run this belt, others don't. Give us your VIN or the number off the belt currently on the truck and we'll confirm before you order.
Is this the same belt as Gates 4080811DF?
Yes, same belt - Gates 4080811DF crosses directly to this part. Different label, same 8-rib, 2058mm spec.
My old belt number is worn off, how do I know if this is the right one?
Count the ribs and measure the full loop length if you can - 8 ribs, 81 inches around is what this one covers. If you're not sure, bring it by the counter or call in your VIN and we'll match it up.
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.