Here are some photos of the gaskets that are mentioned in the Shop manual. One is a thin paper gasket between the two halves of the AC. I do see some residue underneath it may have been the foam gasket that Gdads51 mentioned. The other photo is what looks like it may have been felt or cork and it sits between the top of the air horn of the carb and the body of the air cleaner that is mentioned in the shop manual
Chris
G.O.T. (Good Ol' Truck), 1953 Chevy 3609 AD 3/4 ton with original 216 c.i. engine, 4 speed transmission, stake bed