I dont know if low diff fluid could cause this type of noise or not.
Check all of your sway bar connections too.

 

sway bar connections? the rear sway bar probably is past due for new bushings and what not, I did notice where the rear sway bar mounts to the frame (through the thick clamp down bushings) that there was a bit of a clean spot on the sway bar lust to the side of the bushing, like it slightly moved to the side and slid through that bushing mount just a bit (maybe a 1/4" of clean spot) I will try to take a picture later if you don't know what I mean.

just wasn't sure how that would be a part of this problem. It sounds mechanical and could possibly be coming from the rear driveshaft.

 

Have you made sure all your exhaust system boltts are tight? Mine leaked right at the Y pipe flange due to a burned thru gasket. It clicked like crazy.

 

the clicking is definitely related to the drive shaft or rear axle/wheel. after listening to it some more today I am thinking it is the U joint in the back, it is tough while driving to determine where a sound is coming from, to me while driving it was back and right so I figured right rear wheel, but back and right could also be the rear drive shaft and the rear differential.

 

I have the same issue and it has since started to lock up in the rear randomly. From what I hear there is a pin in the rear diff that can back out and rub against the splines on the diff. May have to source a new rear differential.