I have found a hidden number inside the fiberglass on driver side about 1 foot above the striker plate, the only way to ever see this number is to cut open the glass, very very well hidden,
I would guess only a handfull of people have ever seen this number, I had to change the fiberglass around striker and fender due to an accident, this is how I found that number, guess I should have taken a pic. too late now. Mike. 1969 s2.