The professional glass installer I had put the front and rear glass in my 1970 e-body used the primer. It was nasty stuff. He also used a foam stip to form a "dam" along the edge of the glass, set back about 1/3 of an inch on the inside before he applied the bead of urethane. It helped keep the glass from settling in too deep once the glass is set. It also left a nice inside appearance (not that you can really see it). He also replaced the stainless trim before the urethane set up, so the depth would match the trim's depth. It was a two man job, they were very experienced and the results are very good.