I need to have a tranny rebuilt for my 73 Roadrunner that I'm putting a mild 440 in. I have a couple core tranny's One is a motorhome tranny with 50,000 miles on it the other 3 are just car tranny cores that I picked up. The only one of the car tranny's that I actually saw work didn't have a tranny cooler ( it had a hose connecting the cooler lines at the tranny) and the detent wasn't hooked up. Which one should I have built? Will the motor home tranny have the better parts in it? I know the tail shaft will need to be changed. or will one of the car tranny be best?

They are about the same ....use the cleanest one.

Find the part numbers stamped in the drivers side pan rail and determine the origin of the car units...not all are born equal.