Sounds like mine when I lifted it. Long story short, it was my drive shaft. I needed to convert to a CV type shaft even though my drive shaft angles were within limits.
I didn't believe it until after I actually tore my trans and cases apart and found nothing wrong. Finally gave in and changed the rear shaft to a CV type. Had to cut off old spring perches to rotate axle for proper CV angles. No more noise.
Rotating your spring perches may also affect your shock mounts and E-brake cables in some cases. Depends on lift and how much you have to rotate.
This.
I also want to add, check your CV joints on the rear drive line... One might be slowly wearing down which would explain the progression of the noise your hearing. best of luck!
