Vibration/clicking in drive train when under load?

Heres the deal. I have a 2001 Cherokee sport with 6.5 inch lift, 33X12.50 tires, np231 with AA SYE kit, AW4 Transmission, Cryo 8.25 rear, LP Dana 30 front . When I first installed the lift and the SYE (november of 07) I had no issues with the drivetrain what so ever, No vibes...nothing. About two nights ago I was driving home from a 4 hour trip, about 2 hours into the trip I started hearing a vibration/clicking noise coming from my drivetrain when it was under load. There is no noise when I am coasting or in park.

The things I checked and were fine...
U-joints.
Ubolts.
Transfercase (I took it completly out and pulled it apart and everything was good).
All hardware.
Transmission mount.
Transmission fluid.
Driveshafts (lubed).

Does anyone have any suggestions? Maybe Rearend, Transmission? Has anyone had this type of issue before?

Since you live in Pennsylvania; did you have the tcase engage in 4 HI..... due to snow or bad highway conditions...
I realise this is far fetched, but check the unit bearings for the front hubs...

It does it in 2H, 4H, and 4L... Foward and Reverse. I was going about 60 MPH when I noticed the noise.

There is a inspection cover on the bottom of the AW4 bellhousing which allows you to look in where the torque converter bolts to the flywheel... Check the bolts holding the torque converter to the flywheel... They have been known to loosen up causing the same noise you describe...

I will try that. Thanks.

How old are your u-joints? They can feel good but, did you remove to check the pins.. was there grease in them?

I'd say check the drive line u-joints one more time. Mine did the same thing just a few days ago... Same long trip, then "new" noises/vibration. My driveshaft "felt" fine, but I dropped it anyway just to make sure.

Sure enough, one of the u-joints in the double carden end had worn through the cap and started eating away at the trunion. New driveshaft u-joints obviously solved my problems...

I will recheck them before I get into working on the transmission. Thanks