Perhaps this is the key? I don't know very much about differentials, but it occurs to me that wear might increase the stress. Mine has some lash and clunks when shifting from Drive to Reverse and back to Drive. I don't feel anything while driving when I go on and off the throttle, but I wonder if this could be doing any damage.
Did 7.25's break a lot when they were new, or do they break more often after 40 years and 200,000+ miles of wear? Is there any preventative maintenance that will prevent them from breaking in the future?
