this may sound stupid but i had the same issue with a 93 xj last year. turned out the lug nuts were loose. tightened them twice a week. the actual problem was the carrier going out. come to find out that chrysler corperate axles tend to get cracks in the carriers & that just goes down hill. i swapped it out with a dana 44 but you can just rebuild it cheap for like $100 or so . or lock it for $200. just food for thought

93 xj stroked 4.2 w/4.0 head avenger supercharged 6.5" long arm 35" buckshots rubicon 44's front & rear