http://www.youtube.com/watch?v=14Owyfn_q0k
Well, I guess this changes the course of the project. I will be swapping in the 4 bolt rear earlier than planned. The new plan is to build the drivetrain to handle around 450, then working on getting the engine to that point.
I was around 105 when it started to howl really bad. I figured a tire was starting to fail, then came the loud grinding, which convinced me to pull off. I thought maybe that nut in the tranny finally came off, or the yoke fell apart in the transfer case. I check under it and everything was clean (except the engine, just because it always leaks). Then I looked back and the entire differential was covered in oil. At the point I just said I'm not dealing with it tonight and had it hauled back to the shop.