From time to time seals with the hub will leak and need to be changed out.  It does not seam to uncommon to have the inner hub seal leak. I had the dealership replace 3 or 4 of them so far while under warranty.  Now that is out of warranty, I do them my seal.  So far I have only had the replace the left rear outer seal and that was easy and will be repairing an inner seal soon on another Hummer.  I will let you know how that turn out soon.

One tool that is recommend to get is a "Spanner Socket" for the clamp nut. But it can be done without one.
 

	Here I have the spindle and old outer seal removed.
	This here is the mark left by the sand, dirt & mud that got in between the seal that caused it to go bad.  I polished the surface to help from wearing the new seal out before re-assembling.
	Here are some of the parts that will come out while repairing the outer hub seals.