It's pretty easy, but if you have a trac-lok you will have to use synthetic oil and an additive.
Just unbolt the cover, and let it drain into a pan. wipe the inside out with a papertowel to remove sludge. Clean the seal surface with a wire brush or emry cloth. Make sure to remove any RTV sealent. Don't use sealant with putting the cover back on. get a cork or cardboard gasket and put it on dry. You will thank yourself every time you have to get in there afterwards. Once everything is clean, inparticular the sealing edges, then just put on the gasket, bolt it back up, and put in 1-1/2 - 2 bottles of gear oil or until you can reach you finger just inside the fill plug and feel that the oil is up to the plug.
