When you have your diff fluid changed, does friction modifier show on the parts list, or is it in the synthetic lube like Royal Purple? I asked b/c it wasn't on the list, and was told that it was put in my factory limited slip 8.8, but it's been around 100 miles, and on tight turns it has an audible whine, and you can hear it clunk as you go, like the limited slip is about to kick the bucket. If I bring it in, should I make them replace the diff if they left the FM out? Thanks.

 

They left the FM out. Clutch packs are toast. Getting them replaced on monday. It sure is fun to drive around right now.