98 rodeo rear end jerk-growl

this is my first post.... i have really enjoyed lookin at this message board since buyin my rodeo... at 130,000 it seems like a good truck.... its been mistreated some in its life but im tryin to nurse it back to health... i have this jerk growl noise comin from both rear wheels just as you stop or take off from a turn only.... it dosnt happen from a straight stop... when you release the brake and just ease off it will make the noise for about 4 or 5 wheel revolutions the quietens down and does fine. ive cleaned the slip yolk it was tight but movable... i took apart the rear disc pads and emergency brake shoes cleaned them scuffed with sand paper .. added limited slip additive .... i have had chevy positrac make the similar noise after not putting in the additive.... checked sway bars and rear end mounts all good.... nothing ive done has changed anything.... my first thought is a rear brake problem but cleanin like i did should have at least made some difference ... just doin it on or after a turn kinda makes me think i have differential problems..but he noise is definately in the wheel but i realize the noise can travel down the axles to the wheels... can someone please give me a sign? thanks

sorry...this might help... its a 3.2L 4x4

did you drain and refill the rear gear oil?

Drain/refill differential

no.... i just added limited slip additive. exactly what do i put back in. thanks! i owned and operated a tire shop 12 years until 1995. hence the name "soreback" but ten years of workin at the postal service stole what little memory i had of my undercar days! we used to squirt 90 weight out of a five gallon pump can in everything... but i know times have changed... again thanks so much