You guys can see the setup below. Had read on the web (after-the-fact) that someone had read Powertraxx doesn't do well around 400hp. Well, I think I can put that theory to rest.

I had thought the problem this whole time was with the driveshaft/carrier bearing/axle. Well...guess what remained intact, but ruined the ring-pinion? It broke off two teeth, then skipped a few and broke one more off. Apparently one got thrown into the heavy duty differential cover I had and cracked it all the way through

So, what do I replace it with - Auburn or Eaton? Another?

I'm going back with the 3.73s and the posi and a new heavy duty cover.