Clunking noise????

When going uphill and only to the left when under power I get this hellacious clunking noise under my feet. It goes away as soon as I straighten out. Also it only happens at speeds over 35mph. I have changed axle u-joints, had the driveline checked, the transfercase rebuilt. Anyone ever had this problem? It's driving me NUTS!!

Since you don't have any info posted about your Jeep; I will assume you have an automatic transmission....
A common problem with Jeeps and the AW4 transmission would be loose torque converter bolts...
Remove inspection cover on transmission bell housing and check the tightness of the bolts which attach the torque converter to the flywheel.
They are prone to loosening up!!!!

Check the wheel bearings, I had a the same thing happen to my old '94. I spent hours taking things apart to find the problem. I was shocked because there was only a slight grinding in the bearing. Changed the part and she was good to go! Worked for me, I hope that this helps you.

Also check your transmission mount. Mine had compressed over the years, allowing the exhaust pipe to hit on the support. Only happened when it was going up hills, sounded like a bearing problem.