Diff getting blocked

I have the prob: the diff with time is turning less freely, and actually starts to slow down the car!
When i lift the back of the car on the jack, and put in the neutral, then try to rotate rear wheels by hand, they go very hard.
My first guess would be that a lot of metal dust has accumulated in differential oil, as the car has been drifting a lot.
I also have hit a curb, which has left some marks on the diff cover. What do you guys think?

Change your diff, it doesn’t take long and you can pick one up for under $100 that works fine.

And how do you change oil in it?

He said your diff, not the oil in it.

First, how the hell did you hit a curb and mark up your DIFF? That barely makes sense without fucking up other parts of your car…

Second, if you can’t find the figure out how to change your diff oil, get a Haynes or bring it to someone who knows what they’re doing.

I’m going to hope you’re ESL.

sounds more like an issue with seizing rear brakes to me.

No, brakes are fine, Esl guy, come with me, i’ll show ya how yo get the diff on the curb without even marking anythin else:))

u would hit the tank before the diff