I have experianced many a goose chase for the "correct" part, in my travels i have learned that oddball parts are best found either online or at model or manufacturer specified parts stores. also like desertdog said the aftermarket parts may be slightly different then the original or old replacement even. Also Never Ever trust a parts store like Kragen or Napa, I have run into too many aftermarket parts for my classics that have either broke in the first two weeks or dint work to begin with. im sure others already know this haha.

Shovel all the coal in, gotta keep it rollin! .
1958 Chevrolet Apache "32"