I'm replacing the front vent window rubber moldings on a '50 Olds and had to drill the old rivets out to remove the window from the outside frame. I need a source for replacement rivets. I susupect that most 50's GM cars are the same. It appears to be a stepped rivet with the shank at the top where it goes through the movable piece (window) being a larger diameter than the part of the rivet that passes through the frame.
Thanks,
Bob

Big Flats Rivet Company in Horsehead NY will surely have what you need, and the tool for setting them.www.bigflatsrivet.com/