I'm going to start this thread by saying I have been searching for a solution to this problem for about 3 years, and that includes every forum and google thing I could read. Also been to a few shops but still no resolve. I have seen tons of threads on forums and from what I can see I have tried everything they did that fixed their problem but mine has not yet improved.

Problem: Around 65 mph I get a vibration that comes and goes every 1.5 seconds or so. The faster you go above 65 the worse it gets, and it gets bad. I can't really tell if it changes much under throttle or not.

Maintenance:
1) Brand new and also re-serviced Tom Woods front/rear driveshafts
2) Brand new BFG K02 tires
-Put new tires on old wheels first, same problem. Then installed new tires on new wheels with no change.
3) New wheels
4) Rebuilt transfer case
5) Reshimmed and proper driveline angles
6) Alloy USA heavy duty ball joints
7) Tcase mount
8) Motor mounts
9) New gears
10) Advanced Adapters SYE

We've had the jeep on jack stands and still can't figure out the problem. When just the rear up on jack stands and at 65, there is a consistent vibration. When we put the whole thing in the air in 4wd high, the jeep vibrate way worse. Driveshafts spun great with no wobble and all other moving parts were super tight. Tell me your thoughts!

 

Isolate the front/rear by removing one drive shaft at a time.

 

This has been done too actually (had each of the driveshafts rebuilt by tom woods). The vibration was not really there when either driveshaft was out of the car. It does seem to be much better with the front driveshaft out though.

 

Can you post pictures of your drive shafts? Specifically where they telescope and at ride height? When I first got mine from Adams, it was too short. It worked just fine but caused the same vibration you are describing. Ended up having them make another one that was the correct length and it took care of the problem.