I have a leak out of my rear window on the left side, Any ideas where the most common area it coming from.anyone else have this problem, 2000 f150 SC with slider in window, ( not leaking from slider but top corner)

 

This is a very common problem with the poor seal that occationally occurs from the factory in the rear windows on the F-150 trucks. I have the problem with mine and I have two friends who have the same issue. I just keep a towel draped over the rear seat of my truck to catch the drips when it rains. The alternative is to dismantle the molding and headliner around the window and reseal it with some sort of silicon.