727 manual valve body-Reverse is slipping BAD, All other gears seem good - Pressure tested

Does it slip on first engagement into reverse after starting the engine? I and a number of others have experienced this on 904's. start cold engine, put in reverse and the trans acts like it is slipping really bad, put in neutral and give a bit of gas, let off and put in reverse again and it feels good. seems to be typical for 904 don't know if the other trans does same thing.

Nope. I'm aware of that issue and it's not that at all. I've let it run in neutral for a long time and checked fluid levels. Never gets any better.