I have put a 5.7 hemi in my 66 coronet. It has the original 727 in it. I had to buy a new torque convertor from TCI to get them together. We finally got it running yesterday and it was running good. We decided to pull it out of the garage and take her for a test drive. As soon as I put it in drive, it stalled out. After that I tried starting it two or three times but it wouldn't turn over. Then suddenly it seized up and wouldn't even turn the motor over. It felt like the transmission was seized up. Today the guys got it running again, drove it about 100yards then she started bogging down and shut down again. Then it started not turning over again. I don't think its a motor problem. I don't know jack about transmissions. What does this sound like?