first off i have not started the internals swap so not exactly sure what i have inside but have a 1970 alt motor with case damage, timing hole threads, motor mount breakage, primary lip broken so i picked up a 1981 case in good condition to swap out. i believe the earlier motors had a side oiling pinion shaft and later model has end oiling but if i use the early cam cover will i have troubles? i will double check the oil hole positions between the two cases as i believe there will be differences in the hole locations for the oil pump but as i mentioned i have not started the swap so old motor still in the bike. any other troubles anyone can think of before i open the can of worms? i realize the pinion bearing will need to be checked for fit and cam bearing replaced. i think the factory may have changed the thread size between the early and later model lifter bases also but unsure. this may end up being a winter project.