what the *^&$(#@*&$&%(#*@&$%*!!!!!!!!!! Help?

[Tom]

Ok so as we all know, I have a 99 vortec 350 in my 79 pickup. It used to be backed by a th350. I went to the junkyard and bought a used 1pc rear main flaxplate when I get the engine. Ran it with the th350 for a while, till I got massive knocking. Thinking it was the th350, and since I wanted a new tranny anyways, I replaced the th350 with a 2004R. While the th350 was out, I found my problem. A MASSIVE, 360* crack in the flexplate. So I went and bought a brand new 1pc rear main flexplate. Had this going for about 3 months or so now, and its starting to make the kncoking noise like its cracking again. Ill check somtime this week, but Im almost 100% posative its another f'ed flexplate.

So my questions are, what the heck is causing these plates to crack? They dont do this normally, so somthing is wrong. What do I need to check? Is there a stronger flexplate avalible to purchase? Thanks.