I was out on a trail yesterday. I was in 4 wheel drive obviously then heard a pop and no more 4 wheel drive. I checked all the usual axle shafts, u joints etc. I am going to dig into the front end this evening and wondered if anyone had some ideas. Heres whats working and not working. In 4 wheel drive my drive shaft is turning and my dash light is coming on but wheels are not getting power. I have a 1990 XJ with the 231. I drove the 125 miles home at 70 + with no problems at all.