Thanks for your helpful ideas. Any life I get out of it is more than it had the way it was. Since the transmissions are not available, it was worth fixing it.You are now in real trouble as that case is filthy on the outside
These transmissions are assembled in clean rooms because dust you can not see will wreck them in no time flat
Your chances of getting it back together without contamination is about the same as winning every state lottery twice .
FWIW before I touch a case screw, trannies get blown clean, degreased, pressure washed , soda blasted, low pressure washed & blown dry .