What This Air Spring Does
This is a rear, drive-axle air spring with a reversible-sleeve design. The bellows rolls over a piston instead of folding like a convoluted bag, which gives a softer rate over a long stroke and keeps the frame at ride height as load changes. It carries the loaded weight of the tractor and works against the ride-height valve on the axle.
Key dimensions: roughly 12.5 in maximum diameter, 7.75 in compressed height and 24.5 in extended height. The top plate uses blind nuts. The bottom is a piston mount, and the bottom stud is not included with the bag, so plan on reusing the hardware off the old unit or sourcing it separately before the truck goes back on the road.
Failures are usually mechanical, not mysterious. The sleeve chafes on a torn or missing bump stop, cracks from ozone and road salt, or splits after the truck is run down aired-out. Air leaks at the top plate blind nuts are also common once the studs have been over-torqued. A bag that runs dry against the piston shoulder will fail again fast if the height valve is not corrected.
Why These Numbers Cross
W01-358-8864, 1R12-1097, AS8864, 66666, C81-1011, 03-08716, AS88640, TR8864 and AS-8898 all describe the same physical air spring: same bellows family, same collapsed and extended heights, same maximum diameter, same blind-nut top plate and piston-mount bottom. The differences are the brand that stamped the number, not the geometry.
The reason the list is long is that suspension builders and truck OEMs each assign their own part number to a bag they buy in. Peterbilt catalogued it under 03-08716, Kenworth and Paccar under C81-1011, and TRP under AS88640. The air spring suppliers and the aftermarket lines carry their own numbers for the identical assembly.
Because the mounting interface and the height range match, the part swaps in without modifying brackets, plates or piston. That said, a cross-reference is a starting point only. Confirm fit by the number cast or stamped on the bag you are pulling off, or by decoding the truck's VIN against the suspension build, before you order.
Before You Order
Get the truck on level ground, air the system up, and read the number on the old bag. Reversible-sleeve bags of similar diameter can differ by an inch of collapsed height, and that inch changes ride height and axle alignment. If the label is gone, measure the compressed height at the top plate and check the piston diameter against the 12.5 in maximum bag diameter.
Replace air springs in pairs across an axle. A new bag next to a tired one loads the axle unevenly and drags the height valve into constant correction. While the old unit is out, inspect the bump stop, the piston for cracks, the air line and fitting for chafe, and set ride height per the truck's spec after installation.
W01-358-8864 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to W01-358-8864. 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 | AS8864, 66666 |
| Goodyear | 1R12-1097 |
| Kenworth/Paccar | C81-1011 |
| Peterbilt | 03-08716 |
| TRP | AS88640 |
| Torque | TR8864 |
| Triangle | AS-8898 |
Frequently asked questions
Does the bottom mounting stud come with the bag?
No. This air spring ships with the blind-nut top plate and the piston-mount bottom, but the bottom stud is not included. Pull the stud off the old bag or have a replacement on the bench before you start. Check the threads and the seating surface before reuse, because a damaged stud will leak at the piston.
Will this fit my Peterbilt 389 without checking anything?
Treat the cross-reference as identification, not a fitment guarantee. It is built for the Air Glide 210 low-leaf rear suspension and the matching Kenworth rear air suspension. Confirm the suspension the truck was built with using the VIN, or read the number off the air spring you are removing, before ordering.
Do I have to replace both drive-axle bags at once?
It is the right call. A new bag and an old bag on the same axle sit at slightly different heights and load the axle unevenly, which pulls the height control valve out of balance. Replacing the pair keeps ride height consistent and saves a second teardown when the old one lets go.
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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.
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