Don't really know. I bought the motor and trans out of a running car (64 Polara) both had been built but I don't remember all the details. I had gone to see the car and hear and drive it. Then the guy pulled it to change to a big block. It was a show car already, not a rat that he was fixing up. That was maybe 6 or 7 years ago and I put the whole thing into my car. I've probably put 15k-20k on it. I don't know for sure as I had years where my odo didn't work. However I have found someone who is an expert with these transmissions. I'm just going to drop it off at his shop and let him go through it and see what he finds..