VIN plate missing rivets???

I am currently looking at purchasing a 1964 Plymouth Valiant. Although the fender tag is in place and you can clearly tell that it is correct for the car I have a concern about the silver v i n tag that's on the driver side door pillar. Both of the rivets are missing. It does not appear as though there are any scratches which might show signs of tampering but I am not familiar with this year whatsoever. Can someone out there please tell me if these cars were ever made without rivets attaching this Vin tag?