The inner seal is stuck in the transmission housing (it's shown stuck in the second photo, but now missing the lip rubber). It:s full shape can be seen on the right in the picture of the new set. It must slide off the spline, but it's a tight area to work, and it stuck. I've tried needle nose pliers, and vise grips with a slide hammer attached but can only grip one side due to space limitations. It won't budge. Anyone ever had this problem? I need some ideas.

 

pull out the stub axle first
then use a universal seal remover.
It's usually a good idea to have a service manual on hand for this kind of stuff.
GM provides it for only $30 for 3 days and you can download and keep as much as you want.

 

what he said.
for install there is a special tool designed to seat the sleeve the appropriate depth.