So I changed my diff. oil bc its was making a little noise and kinda bumpy when I turn. I looked in thier really good not metal chunks. Cleaned out the small shavings from the plates and filled it back up with castrol synthetic with limited slip additive in it already or alteast it said it was for limited slip on the bottle. Anyways my rear diff is making even worse noise and is even bumpier when turning. Can I just buy the limited slip additive and put it in thier or am I looking as worse problems? Thanx yall.

Yep, you can buy a small container of the limited slip additive at any auto parts store. Sometimes that will quiet it back down. That's what we added to my son's Dakota and it worked.