Easiest 727/904 rebuild thread...
At this point the pressure plate in the bottom or piston I think it's called just slides or pulls right now. There's a seal on the inside of the drum itself around that center piece where the snap ring came off. It's lip faces down and then there's a lip seal around the outside of the piston... That's probably only goes up and down maybe a quarter inch or so to lock the clutches and steels together...