Leaking Pinion Seal...8-3/4 ???

You have to use a new crush sleeve (or solid sleeve with the correct shims) to get the preload on the pinion bearings right. That also requires that you have an in-lb torque wrench to set it. If you just pull it apart, replace the seal and put it back together you will be pulling it apart again in a few thousand miles to replace the bearings.

If it's an 8.75 pull the center section and work in it on the bench, so much easier to get the preload right.