Usually have to send them out to rebuilder as mentioned. Brake wholesaler in my area don't even repair or sell parts, just send out. Carter's used to have a kit listed, not sure now, they were having trouble getting when I was looking into it. The shop manual has the repairs in it.
Weird someone else can get parts and fix, why not the rest of us?? The big diaphragm in canister is leather and dries out. You put a little oil in canister to keep it wet. You may be able to by-pass the unit with a line tee and small line or couplings, etc. I ran my 54 for 4yrs with out the booster working and had manual brakes. It was still in system tho. I once had a 76 F-600 U-haul truck with same booster or similar, think it would work on the Chevs, maybe newer truck in yard would still have usable one on it? I've never found a working one on trucks sitting for many years like I usually buy! :rolleyes:
