O.T.
When you take them apart, the numbers should be on all the components. You will have an inner seal inside the housing, a tapered roller bearing and race, then an outer seal. Mine all had numbers on them and they were available. Watch for thin shims on the cover plate that holds the outer seal and bearing in place. It is the cover that has 5 studs w/nuts holding them. These shims determin the axle end play from the left and right axle. Dan Shavers says it should be around .010 axle endplay. You can check it with a dial indicator--one that checks brake rotor out of round works best.
Note, the inner seal keeps the gear oil from getting to the bearing and there is a grease fitting that services the bearing.