Correct, it's not the thing under the rubber boot, that is the slip joint and just slides in and out and should have a grease nipple on it already.
The joint at the transfercase end is a dual carden joint, it has a uni and a centering ball in there. Have a look at this link it shows you how to rebuild it and will help with the terminology.
http://www.myjeepxj.com/index.php?pa...-shaft-rebuild
Cheers
Steve