I just bought a 1969 Dart that I am parting out and it had some holes along the windows that look to be for trim, I can't find any pictures of a car with this though.
I had stripped a 68 GT one time that had lower window chrome in the same spot, so yea i guess it was an option on some models.
Matter of fact I might still have it kicking around lol
it is stainless trim-- snaps in place & your good to go.-- not sure what the price point was to decide if your ride got this or not-- my convert has these .Lawrence