If you can do some your own repairs and can get the part numbers, the internet is your friend. You may find the part numbers in the Gillig manual that should have come with your coach.
In my Gillig "parts" manual, the bag is called a "spring" on the Rear Neway ARD 75-6 Suspension. There are 5 rear suspensions described and a couple of front suspensions.
I read about a CC owner who was charged a premium for his $2,000 worth of Dash AC repairs because his ac compressor was no longer made. Yet, for about the same vintage coach I found my replacement on the internet. It was very competitively priced and got the compressor replaced and system recharged for about $600.
Also, there is a much more active CC owners forum at:
You will have to register, but there is lots of thread history to be searched, pictures to view, all from as far back as 2001.
Hope this helps.