LOL...
350 bucks for a used 4 speed? good luck..
most people cant give 4 speeds away, let alone command top dollar for them.
you might get 100-150 bucks or so for it if it were a GP, GY, or 4A, but being out of a 80 caddy, its most likely a GC, and those trannies are the least desirable ones out there.. unless it was rebuilt like 400 miles ago.
sorry to rain on your parade, but i figured you might want to put a reasonable price on it, to get rid of it faster.
the rest of the prices are very fair tho..