Hello, i restoring my Buick GS 350 / 1971 ( frame-off ) it has run 90.000 km / 56.000 mls the TH350 shifts good all time and now i don't know what i should do with it befor it goes back to the car - only new oil ? - buy a rebuild kit ? - give it to a repairshop for overhaul ? only thing i know for sure, is installing a new oil pan ( for easier oil drainage ) thanks Markus
With only 56k miles on it, I would change the oil and filter and put it right back in. I wouldnt even touch it. If its not broken, dont fix it!