Grinding/Rubbing sound from rear

Hey guys, So I've been searching the forums for a while trying to find a thread related to my issue. But to no avail. most of the threads talk about sounds coming from the front.

The sounds start when moving from a dead stop. ie. coming out of a parking spot or turning from a red light. It sounds like a grinding/rubbing coming from the rear. I had a shop look at it and said it looks good. I had 3 degree shims and a carrier bearing put in on my OME suspension when I got the Dakar HD leaf packs put in to get rid of the horrible vibrations. This sound is newer.... and I cant seem to figure out what it is. the diff fluid was also replaced a little over 10k miles ago. I may do a fluid replacement on the diff this weekend to see if that will help. But maybe its also the driveshaft angle? I was also thinking of putting in a Tom woods single piece. I heard those tend to get rid of a lot of issues. Anyway....was hoping someone with similar issues in the past can help shed light. Thanks!

 

How long does it last? Is it just the leafs or shackles squeaking?

 

It only lasts for a few seconds until I straighten out. It doesn't do it from a stop if in going forward. And not sure if it's coming from the leaf springs, but they creak on their own when flexing

 

I’d check the rear diff fluid to see if there is any metal.

 

I put in a set of Dobinsons heavy leaf springs and have had a grinding type sound since, I netted around 2.5" of lift. The truck came from the dealer with a 3n1 lift kit, front diff drop, but no rear CB shims.

Here is the trip to the hardware store Sunday...since I live on gravel roads it's hard to capture the sound at home, fyi.
https://youtu.be/l68XpaIRBY8

Had my mechanic neighbor lend an ear and hand, literally he walked alongside the rear wheel well and had his hand on the leaf springs. He said the sound was from the leaf harmonics being off and instead of flexing it was more sliding and popping feeling. I'm no engineer, mechanic or rocket scientists...but started getting input and feedback via here and found this non-ancient thread.

OP did you get any resolution?