Not sure this shows you anything different but here ya go:
http://www.autozone.com/servlet/UiBr...3d8010b6be.jsp Scroll to bottom for the 3.3 Ltr
I have changed the drive belt several times on my 96 GC 3.8 ltr. Should be the same as the 3.3. The tensioner has a 15 mm bolt head and not a hole. Sears has a $30 kit just for drive belts that is really just a piece of long bar stock with a handle and a socket peg on the other end. Comes with shorty sockets that let you get between the tensioner and the fender. Works great.
As you pry down on the bar the tensioner pully should move down and relieve tension on the belt. Even if the tensioner was stuck in position you should be able to get enough force on it to move it down. I had to change the tensioner once because it was stuck in postion and not automatically adjusting. It would however, move when I pryed it down.
If you really had to you might be able to loosen the alternator and get it off that way.