Be careful of this unless you know exactly what you are doing.

IIRC there is a crushable spacer under the flange nut, that sets the preload on the pinion bearings. If you don't replace this spacer and set the load on the bearings correctly you will end up with a hell of a howl from the diff, and premature wear.
To do it the correct way, you would need to pull the axles and diff out, and set it up on the workbench.
Even the easy way with the diff still in the car, you at least have to pull both axles out, to set the bearing preload correctly.

My diff has a weep around the seal, but it will be left until it is a real leak before it gets fixed.

Good luck.

PK