Mmccarty,
I wish you had that part number. The '70-'71 parts catalog lists rear window weatherstrip only for the V/L (Valiant/Dart) bodies, and front windshield weatherstrip for V, L, and 1970 only R/W (Belvedere, Satellite, Coronet, Charger), used with a locking strip. Everything else calls for 2807425 (rear '70-71 Challenger/Barracuda, '71, all other lines), same part number for the front on Barracuda, Challenger, Belvedere/Satellite, Coronet/Charger (there's a different front kit for the full size car lines).
The manual calls for a rubber 'dam' to be applied to the inside of the window, 1/4" from the edge and angled out to the glass edge. The actual sealer/adhesive was applied with a caulking gun into the area between the dam and the glass. Perhaps the rubber part you saw was the dam? It would have kept the adhesive from squeezing into the interior side, and keep the nasty sticky goo from getting all over the interior trim. My windshield was replaced in 1981; I know they didn't use the dam, used too much goo, and failed to make sure the windshield channel was properly sealed because my inside trim was well stuck by extruded goop and there's rust in the channel.
I haven't found a part number for the dam itself, but perhaps it came with the kits listed above. There's a part number for a rear window spacer, 15 feet long, but only lists for 1970 only (all car lines); I think its the rubber pieces used to center the glass in the opening, rather than the dam, despite the length listed.
