front end noise/knocking....whats going on?

[crazywhiteboy]

ok, heres the story.
i took it out sat. all day hill climbing, and driving on trails.
came home no problems whatsoever sat night.
sun. morning, drove out to I-5(approx. 45-50 miles) to visit someone, on the way home i hit up a local wheeling spot. hillclimbs galore w/shale(sharp loose rocks) everywhere. i was in 4wdL in 1st. as soon as i left the place, put it in
2wd and unlocked the hubs. i drove about 5 miles and the the front end started chattering. like something was caught on the axle shaft itself, spinning then catching on something. i got out locked hubs(still in 2wd) and it got quieter. put in 4wd, it goes away xcept for unusual binding turning left and when hubs are locked and in 4wdL something pops when its under load.
can anyone help? if any questions,feel free to ask. thanks

 

[MAKG]

Assuming there isn't something loose in the front suspension (e.g., radius arm bushings), I'd suspect a binding U-joint in the front driveline.

You ought to be able to trip the problem by putting the front end on jackstands in 2WD with the hubs engaged, and turning the front driveshaft and/or front wheels with your hands.