I'm overhauling drum brakes on '65 Abody. What about these gaskets? (I don't see any during disassembly-of course, brake parts may not be factory after 50 years).
Made from closed cell foam sheet think "packing material sheet'. Not necessary. I use a small bead of silicone. If you really really need them, contact Jim Fillmore at Detroit Muscle Technologies, or find some 1/8" thick closed cell foam sheet and trim out your own. Jim is an A body vendor. YearOne probably gets these pieces from him.