what is this trim piece called, goes around door windows

[stottpie]

i need to replace this stuff, as it's all rotted out pretty good. what's the name of it?

http://img190.imageshack.us/img190/8564/img000672011070418501.jpg

that's a chunk of it, was in the very corner

[Erics SVO]

That looks to be your window run channel. I goes down in the door up and around the glass, creating the felt/rubber run for the glass.

[BrianO]

yeppers

Description
This is a run channel weatherstrip for the passenger side of your 1979-1993 Mustang coupe and hatchbacks. This is the weatherstrip that runs in the inside of the window frame in which the door glass rolls up into. It typically cracks in the upper corner and can cause wind noise.

[Erics SVO]

I got some for my car last summer. I just need to do them, and a bunch of other things....