Ive never done the t-case so someone else will have to fill you in on that one. The diff and the trans(auto) i can help you with. Before you get going you are going to need a new diff gasket, gear oil, a new trans gasket, filter and trans fluid(if its auto). for the diff, all you have to do is loosen the bolt holding the cover on and pry it gently free of the housing, you dont want to bend the cover. now is also a good time to do a quick visual inspection of all the internals of the diff like missing teeth on gears and metal in the fluid. to refill it, reinstall the cover and there is a plug on the axle that you can remove. thats where the new fluid goes, just fill it untill its full, and i think you might have to add an additive if you have a limited slip, someone else can clear that up maybe?
For the trans, if its auto you have to take the pan off with all the fluid in it, really messy. a drain plug kit or a new pan with one already instaled makes future fluid changes much nicer. /forums/images/icons/wink.gif The best way to take the pan off is to loosen the pan bolts then pull one corner down to drain most of the fluid, this will let the most of the fluid drain out, making the pan much lighter and easy to take down. That pretty much covers it.
