Okay, here's my quick 'HOW-TO' on removing the rear glass and taking care of the leaks that so many have had.
I've emailed this procedure out to NUMEROUS people and I think that it's been generally tried and true as I know it's worked.
It's a fairly simple procedure that involves REMOVING the rear glass and reapplying the butyl sealant that is used to seal the interior from the exterior.
It should be said that the design for the rear glass was changed with the 2002 models because of the consistent problems that they were having with them.
I am not responsible for anything that YOU do. This is a simple guide on how I removed my rear glass (to install a power slider). Do everything at your own risk.
First, go buy some butyl sealant. It comes in a roll and I think the consensus was to get the 5/8th size. NAPA and your local glass shop will have this.
Now, you're going to have to obtain access to the back of the window where it's bolted to the body of the truck. This can be done by removing all of the plastic moldings at the back of the trucks interior. Some of you will have to remove the bolts that hold the seat belts in as well.
Once you have obtained access to the glass, you will need to remove all 12 9mm bolts that secure the glass into place. Make sure that you hang on to the little brackets that are in place where you remove the bolts.
Once you have removed all of the bolts, now you must cut the old butyl sealant. I did this using a box cutter and a long bladed pocket knife.
Take the blade between the thin metal and the glass being careful to 1) not slice your hand open and 2) to attempt to get all the way down such that you are cutting all the way through the sealant. This is a critical step and, in my case, was by far and away the most time consuming. Be careful to not 'mar' the threads on the bolts that hold the glass with your blade.
Find the neighborhood kid and/or significant other and/or buddy to help you here. You're going to need to 'gently push' the glass back towards the box of the truck. If you feel that the glass is moving slightly however; won't budge, you probably have some more cutting to do on the sealant. I found it easiest to start on one corner and work from there.... individual results may vary.
Push the glass back to your friend being VERY careful to not bend the frame of the glass. DO NOT USE EXCESSIVE FORCE!!
Once the glass is out, clean off all of the butyl sealant from off the glass and around the pinch weld (portion of the truck where the glass meets the truck).
Use the butyl sealant that you had purchase prior to starting and bead the sealant around the glass staying on the outside of the 12 bolts.
Replace glass and resecure all 12 bolts using a 'back and forth' motion to tighten them evenly.
BEFORE replacing all of your plastic, take it around and hit it with some water. Make sure you don't have a leak.
If all is well, replace plastic, do a little dance, and be thankful that it's fixed. If you've still got a leak, repeat the procedure or pay a glass shop to take care of your problem.
Best of luck and feel free to email me with questions. firstname.lastname@example.org
Also, I welcome any additions or suggestions to this procedure as I'm sure it's not totally complete.
**Edited to replace old email address**