I just pulled the motor out of my 91 Camaro to freshen it up and replace it with another motor I had built.

My problem is the bell housing on my TH 400 is cracked right at the peak of the bell housing about 6 inches long. I am going to have this welded as the crack is a little larger than hairline thickness.

My main question is how can this happen, and what can I do to help prevent it from happening again??