1968 vs. 1969 Valiant rear glass weatherstrip

I'm looking for a rear glass weatherstrip/gasket/seal for a 68 Valiant 2DR sedan. I think the part number is 2841826.

Steel Rubber carries this for the 1969 Valiant 2 DR sedan but they claim it's different than a '68....but of course can't tell me why it's different.

Classic Industries lists one for 68-72 Valiants but when I asked them if they were sure it fit a 68 they claimed to have no real basis for their listing.

Does anyone have any better knowledge of this? Does anyone have one for sale, etc.?

Thanks!