Adhesive recommendation for window trim

A piece of the window trim on my 1979 308 GTS fell off and I just got the replacement. I was looking for recommendation on the proper adhesive. The part that fell off was the end cap on the forward door glass. So it was the rubber piece that is at the very top of the door frame on a GTS model. It seals the top corner of the door against the targa top and the A pillar. The piece slides into the metal frame of the door. So what kind of adhesive should I use to keep it in place? The stuff my mechanic used a few years ago failed and I lost the original piece.