[rotorwrench]

There are sleeves referred to as a Speedy-Sleeve that is a thin sleeve with a removable hat section to allow it to be installed with a piece of tube long enough to locate it properly on a shaft. They are available for just about any shaft diameter. I install them with an epoxy adhesive (Devcon Plastic Steel) that has steel particles mixed in to help keep it from moving on the shaft. They are specifically designed to replace a worn seal area and are themselves replaceable if they wear out. If it will clean up relatively well with a red scotch-brite pad then a speedy-sleeve may not be necessary.

If differential oil leaks past, about the only place it can go is into the real wheel bearing. The rear wheel bearing has a rudimentary seal to keep grease from moving into the brake shoe housing. The wheel bearings should be hand packed. This keeps the grease to a minimum so that it doesn't overflow into where you don't want it.