You will find the occasional good buy and price break on impellers when you can cross match them with older Chrysler products.I’ve serviced a few force motors and modified old stock Chrysler parts to fit .I seem to remember water pumps an d the dreaded starter pinions .You really have to have a batch of old stock in front of you to make the size comparison and then do your best to order something near.It has become a real pain in the butt to source reasonably priced parts or (what were very common) comsummables for common motors.I’ve tried to find some parts for 1970’s J/E motors recently only to have the dealer tell me they refuse to order them because any overidge would sit on the shelf forever.