I just did this to my parts car. Why? It was kinda like climbing Mt Everest----because it was there. First off, the GT fastback and interior trim were removed. So I had a somewhat unobstructed shot at it. After cutting/clearing out the exterior rubber as much as possible, I took some needle nose pliers and removed as much black "snot"as I could from the inside. At the end in desperation, I soaked this super sticky "snot" with acetone (use plenty of ventilation) and it seemed to chemically change it where it was much easier to cut/pull out. Once you remove all of the black sealant that is accessible from inside and outside, clear enough sealant from one of the upper corners as possible. I then used various wires strung through this gap as a cutting blade(Go to harbor Freight tools to look at their window removal kit). After breaking about 12 pieces of wire, I cut a spare piece of garage door cable(this is tough stuff) about 18" long and attached through the sealant gap and used two vice grips as handles. Using this as a "saw" I was able to cut through the remainder of the sealant on the sides and top. I then leaned the window down and cut the bottom hinge. You really need two people for this, but I worked through the sun-roof an it went OK. This will take quite a bit of time and patience, but if you ever need a rear window, it'll be on the shelf.
[This message has been edited by carnut122 (edited 02-11-2008).]