Your front differential is a low pinion I bet. With a low pinion you are driving on the coast side of the gears. The coast side is a a steeper angle, also the gear is running backwards. This translates into a pulling motion on the pinion gear. The 8" pinion bearing is very small and easily deflected under heavy load. The pinion to carrier clearance is very small, less then .080". Contact is "normal" under differentials that are set up loose. Setting preload tighter can cure the contact but shorten bearing life.Thats what my front ARB carrier looked like chewed up like that! Pinion deflection is doing that? Im only on 35's WITH a Diamond housing, 4:88's! Everything you guys mentioned on this thread (that I picked up) Ive done that "should" have prevented this. What gives? My rear does not show this problem.
So what we did was clearance the casing by using a flap wheel to take it down to the low spots, and also took a bit off the pinion gear. It clears now anyway.
I thought it was a bad setup on the gears, but the pattern was good. So removing material seemed like the way to correct it.
I've seen the same issues on the rear differential with people who hammer it in reverse. The same force is applied as a front low pinion.