yeah, im in the same boat...i COULD do it, but wow, its hard to make me WANT to...it NEEDS to be done tho, its low and baked...
differential fluid is easier, you should get yourself some sort of pump to put fluid back into the diffs after draining....
first off, a 1/2" drive socket (you know, use a large ratchet, the head should be about 1/2 just makin sure you know what a drive socket is...took me awhile to figure out and im 20 LOL), either way a '*****' large ratchet WILL work on the fill and drain plugs, just so you know
make sure you can get the FILL plug out before you drain it, because if the fill is stuck, and you drain the fluid, oh boy! lol....so once you get that off, you can drain it, then replace the drain plug, and pump in gear oil....not sure, think 90w? eitehr way, you can look it up, fill it up until it dribbles out of the fill plug....the fill plug is the one that is half way up the diffs, the drain is on the bottom...that easy! you should change your transfer case fluid too if you can, the fill plug on that one is HARD to get off usually, its waaaaay up on the side of the transfer case, but same procedure and i think oil weight as the diffs...but that should be a job you can do yourself in an afternoon, leave the tranny stuff for a LONG weekend!