We did this swap about 5 days ago. I worked fine untill yesterday. We were leaving the track and all was good. He stopped at a stop light. Made a left turn to get on the highway. It up shifted to 3rd then that was it. I woun't hit over drive. No according to the instructions, it say don't flip the 4th gear servo plate. We put it in the same way it came out. 1st through 3rd work great. So did overdrive untill yesterday. Any ideas?

 

Make sure its not losing any fluid and the snap ring is fully seated..

 

I would pull it back apart and check everything again. Mainly check the seals and o-rings. Before you pull it apart check to make sure the snap ring is seated properly and its not losing fluid. I dont think you can put the it back together with the 4th servo in backwards.