What This Air Spring Does
This is a reversible-sleeve air spring, not a convoluted bellows. It carries the cab and sleeper on the Peterbilt Uni-Built cab suspension used on long-hood conventional tractors — 379, 377, 378 and 357, roughly 1987 through 2007. Extended height is 14 inches, collapsed height is 4 inches. Get those two numbers wrong and the cab either bottoms out or rides on the stops.
The bag isolates the cab from frame inputs. When it works, road chop and pitch stay in the chassis. When it fails, everything comes through the floor and the seat. Drivers usually describe it as the cab slapping or dropping on one corner overnight and coming back up when the truck is started.
Failure is normally the sleeve itself. The rubber cracks where it rolls over the piston, or it chafes through against a bracket, air line, or a shock that has come loose. Bead seat leaks at the crimped end plate happen too, usually after years of road salt. Once air escapes, the cab settles onto the bump stop and the ride goes hard.
Why These Numbers Cross
All the numbers in this listing describe the same physical air spring: same reversible-sleeve design, same 14 in extended and 4 in collapsed height, same cab and sleeper mounting on the Uni-Built suspension. W02-358-7036 is the number most shops know it by. Peterbilt catalogues the same bag as 29-03200 and 29-02454, and Paccar lists T81-6002.
The rest are supplier numbers for the same envelope. ContiTech shows 68162 and SC29-Y036. Goodyear lists 1S5-186. Torque lists TR7036 and Triangle lists AS-7036. Different manufacturers, different numbering logic, one interchangeable part. These numbers are printed here for identification only — PartStop is not affiliated with or authorised by any of those brands.
A cross-reference is a starting point, not a fitment promise. Peterbilt built these cabs over a long production run and cab suspension hardware got changed in service. Confirm by VIN, or better, read the number stamped or tagged on the bag you are pulling off and match it against the list above before you order.
Check Before You Order
Pull the old bag and look at the mounting. Note the stud pattern, the air port location and which end the port sits on. Measure the installed height with the cab at normal ride height and the system aired up. If that measurement is nowhere near 14 inches extended, you are likely looking at a different cab suspension setup and a different bag.
Replace in pairs where the truck has one per side. A new bag next to an old, tired one will make the cab sit unevenly and the fresh bag will do more work. While you are in there, check the height control valve and linkage, inspect the air lines for chafe, and confirm the shocks are still attached — a dead shock will destroy a new bag.
W02-358-7036 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to W02-358-7036. 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 | 68162, SC29-Y036 |
| Goodyear | 1S5-186 |
| Paccar | T81-6002 |
| Peterbilt | 29-03200, 29-02454 |
| Torque | TR7036 |
| Triangle | AS-7036 |
Frequently asked questions
Is this the same bag as Peterbilt 29-03200?
Yes — 29-03200 is the Peterbilt number for the same cab air spring sold as W02-358-7036. Peterbilt also lists 29-02454 and Paccar lists T81-6002 for the same part. Those numbers are shown for identification only. Verify against the number on your old bag before ordering.
How do I know if my cab air bag is leaking or if it's the height valve?
Air the system up, then spray the bag, the air fitting and the line with soapy water and look for bubbles. A leak at the sleeve or the crimped end plate means the bag is done. If the bag holds but the cab sits low or high, the height control valve or its linkage is the more likely cause.
Will this fit my Peterbilt 379?
It is a direct replacement for the sleeve-style bag used in the Peterbilt Uni-Built cab and sleeper suspension on 379, 377, 378 and 357 tractors, approximately 1987 to 2007. We cannot promise fitment from the model alone. Confirm your cab suspension type, mounting and ride height by VIN or by the number on the part you are removing.
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.