THERE IS OUTER AXLE BERINGS, ALSO CARRIER BERINGS THAT THE RING GEAR IS BOLTED TO,THAT THE SPLINED END OF THE AXLE RIDES IN. ARE YOU SURE YOUR HUBS ARE NOT THE CULPRIT, TO THE GRINDING? IF THERE TAKING A S**T , THEY WILL START DETERIORATING RAPIDLY. HOW OLD IS THE TRUCK , WERE YOU RECENTLY IN THE MUD ??