More than likely you would have known it was out of balance or had too much angle because you would have been getting bad vibrations while driving.
If it was bad enough to destroy your diff bearings you would have definitly noticed the vibrations. Hell my buddy taco'd his rear driveline on the con and welded tubing over it to make it home and drove kn that sucker for a long time and lord knows that was no longer balanced and never had any problems
Blowing arpart your pinnion bearings was most likely bad install setup, especially if its happened more than once.