blew my u-joint out

well, you may or may not know that about a year ago I found a missing bolt in the flange holding my u-joint to the rear axial, and I ended up doing a helicoil to attach it. Well last night I blew out my u-joint shortly after discovering the buckets of torque my hard has at about 3000 rpm in first gear. luckly I was stationary when this happened.

I had just put some seafoam in my gas and crankcase trying to fix a lifter tick. I wanted to test my power with a peel out as i'm fond of doing. When I stomped on the gas, all I got was a loud bang followed by some nasty rattling and clanging. I had visions of my pistons coming out my engine or some such terrible thing. I was actually pleased to see it was just my u-joint.

Do you guys think I caused this with my helicoil? Also I need a new flange, anyone know where I can get one for my 7.25 rear?