What This Air Spring Is
This is a single-convolution rolling lobe air spring for the drive (rear) axle of a Class 8 air-ride tractor. Design height runs about 15 inches, maximum diameter around 13.6 inches, and the assembled unit weighs roughly 14.9 pounds. Load rating is near 7,800 lb at 100 PSI, which is normal territory for a tandem drive suspension carrying a loaded trailer.
Mounting is bolt-in. The top plate is 9 inches with two studs on 5.87 inch centers. The bottom piston is 10 inches with a single center stud. That stud and bolt pattern is what matches the Navistar 3541731C1 bracket — if your bracket takes something else, this is the wrong bag no matter what the old number says.
Application is International / Navistar ProStar built 2006 through 2017 and LT-series tractors running the drive-axle air-ride suspension that calls for 3541731C1. This is aftermarket, PartStop brand, sold with a 6+ month warranty. We are not affiliated with or authorized by any of the manufacturers whose numbers appear below.
Why These Numbers Cross
A rolling lobe air spring gets a different catalog number from every company that sells it, but the bag itself is defined by four things: bellows diameter, design height, piston diameter, and the stud pattern on both ends. When those four match, the part interchanges. That's the case here.
Firestone W01-358-9875 and W01-358-1191 are two catalog entries for the same physical bag — one is the current listing, the other an earlier or alternate build. Goodyear 1R12-432 is the same assembly under the Goodyear system. ContiTech carries it as AS10673 and also under the vendor code 910B1-95P889. Triangle lists AS-9875, Dayton Parts uses 352-1191, and Meritor sells it as FS9875.
Navistar 3541731C1 sits on top of all of them as the truck-builder number. It's the number stamped in the parts book, not on the bag itself, so it's the one a parts manager pulls first and the one that leads back to W01-358-9875 on the shelf.
Check Before You Order
Pull the old bag and read the label on the top plate or the piston. Bags get substituted over a truck's life, and the number in the VIN-based parts book may not be what's actually hanging on the axle. The physical number wins.
Measure the piston. Drive-axle bags in this size family look similar at a glance but differ at the base — a 10 inch piston will not seat correctly on a bracket cut for a different diameter. Check the top stud spacing too, and note whether your bracket uses an air fitting through the top plate or a separate port.
Cross-reference gets you to the right shelf, not a guarantee of fit. Confirm by VIN or by the number on the part you removed before you commit. If the mounting bracket has been replaced or the suspension retrofitted, treat the parts book number as a lead only.
W01-358-9875 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to W01-358-9875. 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 |
|---|---|
| ContiTech | AS10673, 910B1-95P889 |
| Dayton Parts | 352-1191 |
| Firestone | W01-358-1191 |
| Goodyear | 1R12-432 |
| Meritor | FS9875 |
| Navistar | 3541731C1 |
| Triangle | AS-9875 |
Frequently asked questions
Is W01-358-9875 the same as Navistar 3541731C1?
They refer to the same drive-axle air spring. 3541731C1 is the Navistar truck-builder number that appears in the International parts book; W01-358-9875 is the Firestone-style number for the bag itself. Confirm by reading the label on the bag you pulled off the truck.
What's the difference between W01-358-9875 and W01-358-1191?
Both are catalog entries for the same physical rolling lobe assembly — same design height, same piston, same stud pattern. One typically supersedes or runs alongside the other depending on build date. Either number should lead you to this part.
How do I know if the air bag is bad or if it's an air leak elsewhere?
Air up the system and spray the bag with soapy water, paying attention to the bead where the bellows meets the piston and the top plate crimp. A dry bag that won't hold height usually points at the height control valve or a fitting instead. Also look for a bag that's been running folded or rubbing on the frame — that abrasion kills them early.
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.