When you are working under your vehicle, make sure it is supported by secure jack stands. There is always accident reports indicating someone has been injured because due to working under a car that was only supported by the jack. Please do not take any chances.
Our subject car is always making some long trips to car shows and we try to change the differential fluids every 30000 miles. On this change, we decided to do some preventative maintenance, provide some more beef with the addition of a Kenne Bell axle girdle. The design behind an axle girdle is both convenience and support. There is the added convenience of a drain plug, and the heavy aluminum casting has some really meat right behind the axle bearing. There are 2 support bolts that are threaded up against the bearing caps to provide additional support to the cap under heavy torque loading. With gobs of torque going through to the rear wheels, these caps can stretch. This causes the pitch to change on the ring and pinion gears leading to premature wear and potentially a whining differential.
What you will need before you start is replacement fluids (75W140 Synthetic) including the friction modifier, a tube of RTV sealer and a 5/16x18 bottoming tap. The new cap screws provided with the kit are designed to provide as much thread contact as possible to provide the best support. In order to do this, you must "chase" the existing threads with a bottoming tap. A bottoming tap is different that a regular tap in that is will cut thread to the bottom of a blind hole. A regular tap will leave the last couple of threats with a taper on the them and you will not be able to thread the new bolts to the limit until this is done.
The subject vehicle is a 2002 GT. You will require a 3/8 drive socket set, a slot screw driver, a scraper tool and some high temperature silicone and a drain pan. The differential is a limited slip configuration and the clutches require the addition of the friction modifier. People who leave out the friction modifier will start to generate excessive rear end noise and will have to add it anyway.
Start by putting the car up on a lift or jacking the car up as high as possible and supporting it with jack stands. Do not, absolutely do not attempt this procedure with the vehicle supported only by the lifting jack.
Don't support the vehicle with jack stands under the axle this time, put the jack stands on the frame rails ahead of the lower control arm. This will let the differential hang down as much as possible and make life a whole lot easier when you are trying to get at bolts near the top. Once you have the vehicle securely supported by jack stands, start by loosening all the bolts that surround the rear differential pan. There will be a aluminum tag attached to one or more of the bolts that specify the gear configuration of you vehicle unless you have changed the gear ratio. If you have these, don't loose them, we will replace them during re-assembly. Once you have removed all the bolts, slow pry the pan away from the differential housing near the bottom, being careful to not damage the pan. You will need just enough prying force to break the silicone seal between the two mating surfaces. Once you have broken the seal just enough for the fluid to start running, let it run. This is nasty smelling stuff and you don't want to get any on your clothing.