[Richard]

Can you take a picture of the ring where it meets the bag, and another picture of where the bag where it meets the ring. I am sorry but I just don't remember what they looked like on the inside.

If it is breaking loose like that I can only imagine a couple of scenarios. One, do you raise the rear all the way up very often? For example, I learned the hard way that the aux air compressor will run to it's max while the leveling system is still on. I blew a tag air bag by leaving it in level and compressor overinflating the bag.

Second, check the rear panhard bar. If the coach is moving side to side on the suspension it would put a side load on the bag that is it not designed to handle.

I find it hard to think you have had a bad run of air bags to result in three failures in the same axle. Something may be amiss. Your shock idea may be worth looking into. You can't really tell if the shock is good or bad just by taking the lower bolt out and tugging on it. BUT, you can tell if it is completely shot by doing that. I would at least check it out while it's on the pit.