Just got my jeep a couple of months ago, 2005 LJ Rubicon, noticed that when in 4x4 either Hi or Lo there is a loud bang/clank noise when I accelerate or decelerate (torque is applied). I checked my U-Joints (Driveshafts) after getting home from work this AM b/c one of the guys I was out with said that was likely the cause. I did not find any play whatsoever in the U-joints, but there seemed to be a lot of play at the diff and at the Tcase in the front shaft. The rear shaft has no play.
I have not checked the Axle U-Joints yet.
I also noticed a high-pitched (but pretty quiet, I have to really pay attention to hear it) noise that only occurs while the Jeep is in motion. Brakes applied vs not makes no difference, turning the wheel side to side makes no difference, clutch in or not makes no diffence. As long as I am moving, it makes a quiet but noticable high-pitched noise... a constant noise until I stop.
Any help appreciated. I understand that some backlash (rotational play) in the front drive shaft is acceptable, but I know that the sound my vehicle makes under torque is not normal... My friend I was wheeling with has no such noise.