If u have a limited slip rear differential it is the clutch pack assembly inside the carrier unit,simple repair ,i work a t a dealership and have installed a few hundred of these if the tag is on the cover plate it will have the ring gear size -either 8.8 or 9.75 and gear ratio (example) 3.73 or 3.55 are common if it does have limited slip in between those mubers it will have the letter L example 3L73 or 3L55 ,replace the clutch pack assembly part# 6L1Z-4947-A for 9.75 ring gear or 6L1Z-4947-B for 8.8 ring gear size,new fluid 75-140 full synthetic,friction modifier XL-3 and cover plate sealant ,sometimes u can find these cheaper off line than the dealer charges hope this helps, also FYI if the steering wheel is perfectly straight it will not do this only when turning if so it is for sure clutches in rear diff