Well, not actually the rear window, but the fiberglass(?) filler piece that the rear window slides up into. The leak is happening where the body meets the filler piece. There is a gasket in there that must be deteriorating. Anyway, how is that filler piece removed? Is that gasket available or will I just have to use silicone? I would just tear into into, but I am afraid my window channels will disintegrate and who-knows-what-else will break.... I kinda want to know what's involved before I start. Thanks.