Pop on launch

I finally finished up my 87 IROC, put a SD TPI engine in it. Anyway the other day I go to launch and I hear a loud pop from the rear end of the car. I have checked the rear end and the u-joints and they are fine. Im beginning to think this is a suspension problem. When I jacked up the car to check the ujoints I heard a pop while jacking it. All the suspension looked fine. Anybody got any ideas where to start looking? Or could it maybe be a uni body problem. Im gonna put some subframe connectors on it as soon as my wife is employed again.

i would check the torque arm, maybe a bushing wore out

You can also chk. your bushings in your l.c.a..