Here are the gears, these are 2.73

Hopefully will upgrade to 3.73's soon.
The fluid probably was 10 years old, was very thin, but no much wear on the gear, good stuff.
Clean up the matting surfaces, and any grime build up.
mine was pretty dirty, I spent probably 45 mins getting all the grease and oil off, then taking a 80 grit sanding disk, slapping that on the dremel and removed all the left over crud, which revealed a layer of rust, so i sanded all that rust off, put some anti rust inhibotor on, and nailed it with about 4-5 sprays of gloss black in the hot cali sun, was about 75 today.'
This is a good time to lower the vehicle for a few mins, letting anything sitting in the back of the housing to come foward and out. Jack it back up.
Put a very light layer of rtv on the mating surface of the gear cover, then apply the gasket, it will sit pretty firm, if you use to much RVT it will go every where, and the gasket will side around, so dont use much, and it will be easier to take care of next time you change it.
Put the bolts in hand tight, I then torq'd from the top down, pretty snug.
The location of the fill hole is on the passenger side hidden behind the axle as shown. This takes your 3/8 drive and the extension to loosen it, not socket required!