A good local parts store should be able to look them up in their books, probably will have the seals in stock. I prefer the "mom & pop" stores, owned and operated locally, especially if an old man runs it. They know how to look these things up. Napa is also good, depending on the management. Avoid the big, low cost chain stores for these old trucks. They might have what you need on the shelf, but most have no idea how to look it up to find it.
