I have a freshly rebuilt 350 ci engine paired up with a stock Buick 2-speed auto trans. There is an inexpensive TH375 trans core for sale locally that I could rebuild but I don't know if it will fit or not. The seller says it is the same as a TH350 short shaft.
My engine, 2-speed trans, and car is a '69 Skylark. I'm a novice at this and need a little help from you experts!