Everybody keeps forgetting I have an open rear diff - no LSD. But to my understanding, Royal Purple has qualities in it comparable to an LSD additive already. Check it out. The front is easy to drain and fill - the rear I think is easy to drain but a little more challenging to fill. The front is just a bolt that is removed - it is the bolt at the very bottom of the 3rd member. It acts as a bolt and a plug. Once fliud stops coming out, put the bolt back in and fill er up until fluid starts coming out of the fill hole then plug it again. I think we had to pump fluid into the rear diff but it has been over a year and a half ago, so I forget.