Quote Originally Posted by chasracer View Post
The old ones - the one's I consider the good ones have 8 bolts in them. The later stuff has 6 bolts. AS long as you don't mix the pump halves all is good. And TH400 cases usually don't crack so you have something going on that is causing that stress to occur between the engine/trans mounting and the transmission mount. Something is flexing and moving. In the Camaro we used to crack TH350 units on a regular basis, anti-roll bar in the back finally cured that problem because the chassis was twisting so badly.
My thoughts exactly.