c4 swap

I just got myself a C4 tranny. Ive noticed that when i try to bolt the bellhousing to the tranny the prop shaft axle will stop turning? how much should a shaft turn? it goes quite smooth to turn one side, but harder the other.

so i recently swapped the aod in my 91 mustang for a c4. its a stock c4 but has a shift kit. the problem im having is the car doesn't seem to shift very hard under heavy throttle like it should with the shift kit and also it wont shift into 3rd gear until about 45mph. i have the vacuum...