I do believe they are a rivet of some sort. If you look at the dished area on the narrow ends, it looks like they could be peened over like solid rivets would be. Is it possible these are pins for the door window regulator rollers? The dimensions appear to be similar to the ones in the door of my Scamp. I don't know how many rollers an E-body has though. It appears to me that the 8 pins would be a kit for one side since there is only one oddball with a larger OD and three with a longer stepped portion, but I'm just guessing.