The Stovebolt Site Forums The Shop Area General Truck Talk How was the identification plate fastened to the door pillar?

What year?

1950 was probably the last year that small clutch-head hex-screws were used. (those screws are hard to find)
https://oldchevytrucks.com/blog/index.php/2010/02/screw-on-id-plates/

Later A-D years used a non-reusable punch-in rivet - reproductions are available. They were also used on cars & trucks after Advance-Design years.
https://www.classicparts.com/1947-59-Original-ID-Plate-Rivets-pr/productinfo/33-106/