2000 Dakota clicking in reverse

[77fixer]

My neighbor has a 2000 Dakota. Has 4.56 gears that were swapped 4-5 yrs ago and the factory limited slip.
Over the last few days he's noticed a noise from the rearend. He had me briefly listen to it when I ran into him in town. It is only in reverse and more noticeable when turning.
It's what I would describe as a clicking type noise. I could hear it on both sides about equally.
He pulled the diff cover and everything seems ok. No metal bits, etc. The only thing is whether the end of the axle ahaft at the C-clip should be blue (from heat-treat?).
With it on jackstands, drums off, there are no noises. No clicking, no grinding. Everything rotates well, pretty snug which may be due to the limited slip.

Any ideas

 

[arse_sidewards]

I'm betting something to do with the brakes/drums.

 

[MigGunslinger]

If it's a 4X4 just for laughs check if it has a CV joint coming out of the transfer case to the front axle. it gets worn out and clicks while turning and reversing sometimes? I know you said rear end but weird shit happens with noises under trucks.

 

[77fixer]

Sounds can definitely travel. I was pretty sure he'd find something in the diff.
I'll have him check for a CV

His brake shoes are pretty worn, so he was going to replace them. There is no obvious damage or loose parts, but the material on the right shoes are cracked.