It's really not that bad of a job. If your going to replace the rear cover gasket you can go ahaed and rain the diff and not make that big of a mess. The pinion seal is pretty straight forward, remove the driveshaft form the yoke and slide it to the side, you can zip tie it up out of your way and not have to remove it from the transmission. Remove the yoke, the pinon sheild should come with it. The seal should come out with the use of a hammer and a chisel or punch. Clean everything up and replace the seal, they have seal drivers for this or if your easy and careful you can use a soft faced hammer. Clean up your rear cover and install a new gasket, put everything back together, refill the diff and your done.
