1967 Plymouth Valiant 100
That is actually excess glue from the headliner/windlace which I didn't catch until it had dried already. Here are a couple closeups. I don't have any good pictures of the underside, so I will try to put it up on ramps and take some more tomorrow (just got back from an out of town trip this evening). I did find some other pictures of the work on the car, so i will post those in the meantime.
Left and right floor pans replaced (before):
after:
LH Quarter before:
During: