Put pan under differential cover, pull all the bolts off the cover except the top one, which will be only partially threaded on, screwdriver between the axle housing and the diff cover to pry it open to let the fluid drop into the pan, the top bolt is there to keep the pan from dropping and making a bigger mess, once drained removetop bolt and remove cover completely. Clean the housing and the cover mating surfaces. Once clean from all previous silocone, I use laquer thinner to clean the surfaces even more. Then glob on some new silocone, and put hte cover on, and tighten the bolts til their snug. Wait 20mins for silocone to harden, then fill through the fill hole on the front side of the pumpkin. Fill until fluid starts dribbling out of the fill hole. I like to 'overfill' by seeing if more fluid would go in, and it'll just dribble out. Put plug back in, done.
I run Royal Purple in mine, don't remember the weight though.
'01 XLT disguised as a '03 Fx4 Level II
Big. Loud. Slow. Bright.