904 trans problems

We have a 70 Dart. I had put a used 73 904 in it out of another car. When we did it we put a Trans-Go TF-1 kit in it. My son had a kick-down linkage failure and cooked it. Rebuilt the 70 904 and put the valve body from the 73 in it. Here's the problem, when left in drive' the thing wont return back to low. if you shift it manually to low it works fine. In drive it always seems to try to start out in 2nd. Am I missing something between the years?:banghead: