/6 904 transmission swap still having problems....

Hello everyone,

I recently had an automatic 904 transmission go out.. Or at least I think that's what happened. Please give me your opinion on the symptoms I had. All of a sudden I had no reverse when in gear. Also at freeway speeds the engine was revving very high, but I was not flooring the gas pedal. This seemed to happen all of a sudden, not gradually.

I have replaced the torque converter within the last three months, so that is relatively new. I swapped out the transmission with my buddy a couple days ago in my garage. Everything is working, however when in drive, occasionally I will be at a full stop and when I begin to accelerate the car revs higher than normal and then kicks hard into gear and goes forward. This is an intermittent problem, doesn't always happen. I check fluid levels and shifter linkage. Everything appears to be good. What do you guys think is the problem? Did I swap a bad transmission for another bad transmission? The new transmission is another 904 identical to the one I replaced. The car is a 1971 dodge dart swinger 225/6 with 904 tranny and 7.25 rear. Any information or help is much appreciated. Thank you all! Mopars rules!