Not sure man there was some small flecks of metal shavings in the housing when I cleaned it out but not that much at all.
I owned this Jeep before and when I sold it to my buddy it needed new bearings and seals in the rear end it and I think he continued to drive it for a couple thousand miles (like a *******) and had a shop "rebuild" the rear end putting in all new bearings and seals seems like maybe the guy said F it and left the crappy spider pack in there? He said when he picked it up the guy complained about losing money on the job not charging him enough so I wouldnt doubt that he didnt want to replace the gears. But I cant prove this theory.
Seems like the only thing I can think of. My buddy never wheeled it he was a total mallcrawler with it for the 20k miles he owned the Jeep before I bought it back and I dont wheel hard and ya I like to mash on it once in a while and try to do donuts here n there offroad but I wouldnt think it would wear like that most the time I drive like a grandma since its slower than crap with the 31s, 3.55s and 4.0.
The fluid was fairly nasty when I changed it but not nearly as bad as I have seen. It had maybe 20k on the fluid if not a little less. Not sure what kind of oil was in there tho.
Also it is weird that its the drivers side gear that is worn bad on the drive side of the gear and the coasting side is smooth still and the passenger side gear looks fine and just a small nick in the spider gear that is on top in the pic. And the ring and pinion look fine from what I could see but I didnt rotate the gears at all either...