Weird noise from my rear end.
 

As funny as the title might sound...my '92 XJ is making a noise when I take me foot off the go pedal over about 30 mph. It sounds like engine breaks on a big rig. I can't tell if it's from the rear end, the t-case, or the u-joints, but its it only happens for a split second right when I let off the gas. I checked the dif and tcase fluids, both fine. Its got the C8.25 rear and NP231. Any ideas?

Exhaust noise,did you look at your muffler?

Muffler looked fine, hangers are good. It sounds like it coming from the driveline.

Take a good look at your drive line u-joints.

Just an update...I recently took off my aal, cause they were too stiff, which dropped my rear back down about 2" and the noise from my rear end went away. It was obviously a driveline angle issue. Now I know when I lift it back up I need a t-case drop.