GMC 4905 airbag?

[bryanhes]

I have replaced one of my front air bags and have just bought a rear one to replace on my 1970 4905.

My question on the rear bag assembly; Is it supposed to have the thick ring at the top where it mounts. The reason I ask this is the bag I am replacing appeared to be the wrong bag to begin with as the other three on the rear do not have the thick plate attached to the top of the bag.

Is it possibly the difference between a Firestone and Goodyear bag? The Goodyear bag is pictured below. I guess when I get under the bus this weekend I will look to see if the ones without the plate are Firestone.

Thanks,
Bryan

[JackConrad]

Brian,
    I think you are correct, I recently replaced a tag axle airbag on our MC-8 (similar rolling lobe type bag). The new bag (Godyear) looked like the one in your photo. The old bag (not sure of brand) had a top plate that sorta "popped" into place.  Jack

[bryanhes]

Here is a picture of the one of the three that look the same.

[bryanhes]

Here is the one I am going to replace. You can see the difference in the plate at the top

[gm4106]

I was told that you don't want to mix firestone and goodyear air bags. There is a height differences.You can mix them front to back but not side to side. Hope this helps

[bryanhes]

I thought about that yesterday when I called Mohawk about the bag. He said his book sowed height should be 17" fully aired. The strange thing on the oldbag is that instead of the studs coming thru the bottom plate there are two bolts going up thru it, not the way it should be. I will just have to get under there and check it out.

Bryan