For starters, it may not be a 55 motor if you are correct on the date being December 55. Production for 55 stopped at the end of August 55, factory changed over for the 56 model year during the month of September, production for 56 begins October. That would make a December 55 casting date a 56 production motor. For 56, those motors used precision bearings, no shims. You might be using the wrong bearings.
Last edited by Dragsix; 10/15/2023 2:39 AM.
