transmission prombles

I have 97 jeep Cherokee. This my 2nd transmission. I just put a new transmission in and it cracked the case in three days. I put new motor mounts and tranny mount and is 100% sure that I installed it right. If you can please help me out. Thanks.

over torquing the bolts maybe? was it a nwe or used tranny?

Sounds stupid,but do you go thru automatic car washs?My brother has a YJ and was going thru the same probs,turned out the auto wash he was going thru did undercarriage spray and it forced water in the tranny.Cooked it everytime.His tranny shop him told Jeeps and Mercedes are prone that prob.

The tranny is cracking on the very top where the tranny meets the bell houseing.