Have a look under the drivers floor carpet, and under the back seat. You are looking for what I think is called a "Broadcast Sheet" which includes the numbers on that tag plus much more, and is what the guys on the production line work from. This tells them which heater, which radio, trim colours, etc. I've got a 1964 Dart GT (in Australia) and while there's a guy on every corner who can decode tags for later "acknowledged muscle cars", guys who can decode the early pre 1965 tags are scarce, and the Dodge Codes do not translate across to Plymouth. I've decoded most of mine just by watching EVERY SINGLE fender tag thread and writing down the numbers that are the same on mine!
