Have you tried Shoebox Central? The have (or at least used to have) a stock of used vehicles they can get parts from. Otherwise, Southside Obsolete ("barnfind08" on this forum) seems to have many of the odd parts people are looking for. If you can't find the specific bushings you need, there are many sources (Grainger, Mcmaster/Carr, Zoro, or even Amazon) of stock bushings that can be used as is or with a little trimming or reaming.