easy ! take the linkages off your throttle servo, un do the 4 screws holding your diff in, pop it out, un do the 4 screws that hold your diff together, dont touch the one on the outside of the diff on the side, its a locking screw. have a look inside. put the diff back together minus one screw. get a syringe full of whatever weight silicone oil and plunge it in through the hole. screw the last screw in and voila ! id advise using a bit of prepsol light grease while you have it open, these diffs leak when you use them so the grease will stick and protect your diff once the oil runs out.