Diff Dilemna! Need opinions!

Based on your last thread, I realize you might not want to hear this but, I would not be surprised if the problem started with trying to launch your car with big tires and the 6 cyl leaf springs. Most of these problems usually begin with the simple stuff.

You obviously have some repairs to do but you should really consider getting the 002-003 superstock springs, long shocks and correct the pinion angle (in that order) or you may end up breaking things again. You should easily be able to run in the 12s without breaking things with a manual trans as long as everything is in good working order and set up correctly.