Check with a local auto parts store that does not look like a fancy box dropped into the neighborhood.
You should get to know the folks at a local store. Check for a dirty rag or two on the counter, dust on the merchandise displayed, and someone who can find the really old parts catalogues and knows how to read them.
Take a sample of what you are looking for or planning to replace. The counter-guy will take a wire brush and gently clean off some of the grime, figure out the numbers, check the catalogue, and call one or more of his suppliers, then say, "UPS will have the part(s) here tomorrow afternoon."
Just remember, service and parts is not the cheapest, but it is the best.
