Read the assembly process. As far as primer and paint, whatever blew in there was it. Take enough of these apart and you see coverage was limited in that area. When shooting these or any car, it's a pain to get in there for full coverage and a nice uniform finish. I'm doing a 62 Merc for someone and the factory coverage is similar. But they hammered on the paint to a point of very thick sags and hangers off edges 1/4" long. Want to see factory runs just look at a Mopar.