I replaced the 4spd in my 84 brat with one from another brat. The bad part is that when I was tapping on the back of the transmission to try and slide it into place. I broke off a piece of the ring around the shaft were the rear seal sits. Now the tranny wont hold fliud. I tried taking apart the old transmission and swapping out the rear sections but I cannot get the end to come off the old one. Is there some way to "fix" the broken ring so it wont leak? What is the secret to breaking apart the old transmission?

I would attach a picture of the cracked piece. it's one thing to suggest repairs, etc...but there is a lot of variability in "a broken piece". i could see it being simple and repairable or beyond hope, get us a pic.