I had the tranny in my 71-GTX rebuilt right after I bought it in 98. Put it in myself. All seemed to work OK, then it would just stop working and howled a little bit. In that time, the car has been in storage for the last 15 years. Finally took the car back out and it turns out that I didn't engage the torque converter all the way. Ruined the front pump. $600 later, it was fixed right.