I went and looked at a collection of 69 and 70 fastback projects and parts cars this past weekend (non-Shelby). I noticed that the vin tag at the base of the windshield on the interior of the car were fastened by different style rivets so I put any purchases on hold being wary. Some had regular round rivets, some had the flower type rivets (think maybe GM used them back in the day), and one had one of each! What is the correct style rivet? What if any differences are related to where they were made and when? I'm not a 69/70 expert so any guidance would be appreciated