Clunk or Wham and other noise descriptive words while going down road

2000 xj aw4 4x4 125k, This has happened twice now, while driving there will be a wham and you feel the whole jeep jerk and it continues to drive fine. The first time it happened I thought I hit something it shuttered so bad. The second time about a month later it was not as extreme. I did not notice a jump in RPM's or anything. It feels like it was coming from the rearend. Any suggestions on what to check.

i once pulled apart an 8.25 that had sheared the retaining pin on the cross shaft and walked out into the pinion. the owner said he heard a loud thunk and thought nothing of it. drove it like that for a month. needless to say the cross shaft was in 3 peices and only 2 were in the bottom of the pumpkin. could be a possibility. pull the cover and check her out.:greensmok

I could be your Crankshaft position sensor. My 2000 was doing the same thing. The big bang/shuddeer was the engine stalling beliefly at speed. The big jerk/shudder was my rear pinion absorbbing all the shock. the trtuck would only stall for a milisecond, but it was enough to blow out the pinion bearing.

I pulled the rear cover off and it did likes fine in there. How would I test the CPS to see if it is what it is.