2000 crown vic installation issues

I am in desperate need of somebody help, we were having problems with our transmission in our car, 3rd and OD pretty much went out. Anyway thats not the problem, problem is we are trying to put another transmission in and when you get it bolted up the bolt in the from of the motor to turn the fly wheel will not budge, they backed the transmission out and just put in the torque converter bolts in then it turned but they bolted the bellhousing back up and it wouldnt turn again any suggestion on what we should do or what we could be doing wrong would be great.

Sounds to me like the torque converter is not completely seated. You need to be sure the torque converter is completely bottomed out before you try to install or you could crack the pump ot converter shaft.