What This Air Spring Does
This is a reversible sleeve air spring, not a convoluted bellows. It sits between the cab mount bracket and the frame rail, and its only job is to keep road shock and frame twist out of the cab structure. Collapsed height is 3.0 in, design height runs up to 7.5 in, and maximum diameter is 2.9 in. Load capability is roughly 1028 lb at 100 PSI.
The base plate is aluminum with a push-to-connect bottom air fitting. That fitting is the first thing to inspect on removal. If the old bag was leaking at the collet rather than the sleeve, you may be chasing an air line problem, not a bag problem. Cut the line back square and reseat before you condemn anything.
Failure is usually visible. Look for a circumferential crack where the sleeve rolls over the piston, ozone checking on the outer rubber, or a bag that has been running collapsed and chewed itself on the bracket. A cab that leans to one side after sitting overnight points at one bag or the leveling valve feeding it.
Why These Numbers Cross
Cab air springs get cataloged by dimension and mounting hardware, not by truck. Firestone W02-358-7206, Goodyear 1S5-176, ContiTech SC31-W206 and 67452, Triangle AS-7206, Torque TR7206 and Meritor FS7206 all describe the same sleeve envelope: same collapsed and design heights, same diameter, same bottom air fitting orientation, same aluminum base plate. Different suppliers, same physical part in the bracket.
Freightliner 18-29919-000 is the truck-builder number for that assembly as it left the plant. Firestone W02-377-7202 shows up as a related sleeve number in the same family. All of these numbers are listed here so you can identify what you pulled off the truck. PartStop is not affiliated with, endorsed by, or authorized by any of these manufacturers.
A number stamped on the old bag is the most reliable starting point. Rubber parts lose their ink, so if the label is gone, measure collapsed height and outside diameter and compare against the figures above before you order.
Before You Order
Cross-reference is a starting point, not a fitment guarantee. Confirm by VIN or by the number printed on the part you removed. The Columbia is the cataloged model here; Century Class and Argosy COE share the same cab mount arrangement, but cab configurations changed over the production run and sleeper mounts can differ from front cab mounts on the same truck.
Replace in pairs where the mount uses two bags. A new bag beside a tired one changes cab attitude and loads the leveling valve linkage. While the cab is jacked, check the mount bushings, the leveling valve arm, and the height control linkage. Set ride height to spec after install and cycle the system to purge trapped air.
W02-358-7206 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to W02-358-7206. 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 | SC31-W206, 67452 |
| Firestone | W02-377-7202 |
| Freightliner | 18-29919-000 |
| Goodyear | 1S5-176 |
| Meritor | FS7206 |
| Torque | TR7206 |
| Triangle | AS-7206 |
Frequently asked questions
Is W02-358-7206 the same bag as 18-29919-000?
They are cataloged as the same sleeve air spring, with 18-29919-000 being the Freightliner number for the assembly. Same collapsed height, same diameter, same bottom air fitting style. Verify against the number on your old bag or by VIN before ordering, because cab and sleeper mounts on the same truck can take different parts.
How do I know if the cab bag is leaking or the air line is?
Air the system up, shut the truck down, and spray soapy water on the sleeve, the base plate seam, and the push-to-connect fitting. Bubbles at the collet mean the line or fitting, not the bag. A crack at the rolling lobe or a sleeve that has been running collapsed means the bag is finished.
Do I have to replace both cab air springs at once?
If the mount uses a pair, replace them together. An old bag next to a new one sits at a different height and the cab will lean, which puts the leveling valve linkage out of adjustment. Set cab ride height to spec after the install and recheck it after the truck has been driven.
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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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