You asked for it....
Lets see..pop the dif cover to drain the fluid...pull the DS, remove the pinion nut, matchmark and pull the hub the DS bolts to...the seal is right there....remove and replace it...install the hub(on your matchmark) and pinion nut....that nut has to be re-torqued to set the pinion preload correctly...if done incorrectly, it could be trouble...air gun makes it easier to remove and install the pinion nut...
tighten the nut carefully, you cant crank it til its tight....you wind it down, then when almost at the end, take only small turns on the nut...you want to tighten it til you have a "slight" drag to turn the pinion...
just go slow and don't over tighten it...it has to have no "in and out" play and have a slight drag to rotate...
with the rear all assembled, IE, the dif in the case and axles/wheels on, i would use a TQ wrench and see at what lb the pinion nut "clicks" off at before i removed it...when reassembled you would want that same TQ to know you have "preloaded" the bearing correctly...
if you haven't dubbed around with this type of stuff, you may just wanna have it done....
to me, its harder to explain than do....hope that helps???