On a '67 Cougar that molding has a pop rivet attaching it to the end of the rain gutter. Screws attach it to the body outside the window. It could be yours is bent a bit and needs to be straightened. The stainless drip rail molding snaps over it hiding the pop rivet.
Thanks. I know how the drip rail moulding attaches to the J moulding. I was talking about how there is a gap, if you’re looking at the back side of the J moulding, as in looking from the back of the car toward the front, where you can see the unfinished back side of that J moulding. I called WCCC and they said that’s just the way it was from the factory. Maybe it was filled with putty from the factory. It seems weird to me but if that’s the way it is supposed to be, I guess that’s that.