So what IS needed for a gear install on a 00 GT?

Gears
Speedcal or some device to correct speedo
bearing overhaul kit which includes shims, all new race and carfrier bearings
crush sleeve
gear oil(Royal Purple has friction modifier in it)
fricition modifier if not using RP
A good RTV sealant for the rear cover.
Various tools, such as an impact, micro caliper, sockets, flat head screwdrivers, pry bar, etc.

I have a write up on my website on gears.
 
Bearing seperator, bearing puller, pinion depth measuring tool, magnetic base dial indicator, inch pound torque wrench, impact wrench, sockets, prybars, and regular hand tools. Alot of patience, time, and understanding of how its done. If yer a few thousandths off it could get ugly. Its for the people who can pretty much do anything that needs to be done to a car. I hope to try my first soon. Ive done alot of reading tearing apart rears, and have watched it done. Buy gears and a install kit.