I parked the jimmy (1998) last week after I heard metal on metal intermittently about 5 blocks from home sounded like a driveline issue so it sat until the weather cleared and I had time to check out some things.


Found my 4x4 wasn't working, maybe never did, replaced the transmission vacuum switch, wasn't able to test the vacuum module under the battery with the new switch as I wanted to change out the differential fluid front and back first. But on loosening the rear cover and draining out some oil I saw something drop and heard a heavy clunk into my drain pan then found 3 more chunks after removing the cover in the differential.


I can see 2 teeth off the ring gear gone and it looks like the pinon gear has missing teeth as well. As far as I can see the spider gears are okay but I can't see them all that well. I'll have to disconnect the axle and try to rotate all the gears to see where all the damage is.


I figure I'll get a junkyard rear end and check it out before installing assuming just my ring and pinion gear are damaged. Otherwise I wonder if just getting all new gears is better, if costlier than using a donor rear end.



The only issues I had driving were I felt no difference on turning 4x4 on for the few blocks I used it, but it may have never worked, I heard additional noise from the front end but didn't really feel anything but I wasn't on anything slippery. The buttons all lit up and there were no indicators that anything was wrong ie dash lights. It wasn't until after I heard the metal on metal noise and was investigating the 4x4 I noticed the 4 lo light blinked, I think it stayed solid when I tried it a month or so ago.



In 2wd I heard and felt a clunk when reversing from a about a 15-20 angle then going into drive, thought it might have been the gas tank being loose but found out the tank was fine, also thought it might have been the battery not being clamped down tightening the battery seemed to fix the clunk.


So I wonder if the gears were just old, 1998 and seen too much abuse from previous owner, or the non working 4x4 got the t-case stuck somewhere between rwd and 4x4 and that did it, could the clunk have been too much play in the axle and that was the cause, or something else?


I don't want to get a 'new' junkyard rearend to have this happen again or worse brand new ring and pinion gears(assuming the spiders are good) and the same.