64 Dodge Dart 904 transmission issues

Ok sounds have a 64 dart 225 slant six with i believe a 904 transmission. Motor has been rebuilt and is running great. We drive it about one a month between 1-2 hour drives. I moved the other day and drove it to our new house 1.5 hr away mostly 55mph. No issues there. The next weekend i noticed it was have trouble getting into gear. I let it warm up a little longer and didn’t have anymore issues. So the next time i took it out the only way to get it into any gear was high revs, 3-4K. Drove it around town and somehow made it into my garage by high reving it into gear. Now nothing! Can’t get any gear at all. Things i have checked:

Throttling cable- no issues
Push button gear selector- no issues up top or on tans
Drained and removed filter and replaced- no big metal chunks. Just usual soot. But clean
Put everything back and filled and turned car on, warmed up and had to add more fluid to get to level while warm which i assume means pump is working.

Please help! I don’t have much knowledge on transmission like i have on engine as we always stayed away from them