Tailgate Window Filler

I have a problem with my tailgate rear window. The sash rotted out and I have to replace it. I have all the parts, but the "filler" which is a rubber channel under the window is in a million pieces. I called the dealer, but I have to buy a 100 foot roll of it. Has anyone run into this and what did you use for filler? My window is in the up position permantly until I fix this. :disappoin