[66Submarine]

Not a great idea, as you learned. Reverse isn't intended to see a lot of abuse (or any, really) and isn't real strong. If there's stuff on the ground I'd say that trans is probably only good for whatever spare parts aren't broken. You'll obviously need a new case, and as cheap and (relatively) plentiful as these are, I'd say your best bet is to just find another good one for $50-100 and plug it in there. I don't think trying to repair the broken case would be a good idea.