It's not as bad as it seems. It is important for the life of the transfer case to get it right.
The Novak Guide here does a good job. https://www.novak-adapt.com/knowledg...rebuild-guide/
I cut and pasted from there in the previous post. Go to the Output Shaft End Play section. The pictures of the way they measure will tell you a lot. The output bearing has to have a small amount of end play (in and out movement of the output shaft). The cap and the case have the shims between them so you can set the end play. The bearing race can move in and out of the cap and case. The shims harness the movement.
This video does show the procedure somewhat. https://www.youtube.com/watch?v=3l4my1S5kU8
If you need more I can scan the pages from my service manual for you. The Novak guide is pretty good. I do think the Jeep Universal Service Manual is a very good reference. For what you need to do, I think the Novak guide will help.