The door tag only gave information about the truck, size, weight, model, color, etc....
The VIN number is the engine serial number. No where on the body or frame will you find this number. Up to or around 1955 the VIN was this way, after it was changed to what we use now with the number stamped in many places on the truck.
Through the end of the Advance-Design series (1947 to 1955-st series of trucks), and maybe later, there was no model information, or wheel-base information, or equipment-specific GVW information, or exterior/interior color/trim information on any identification code/tag.
The title/registration code "VIN" was often the Engine Serial Number until 1957; but, the cab/Vehicle Serial Number was also used before to 1957 in some states (sometimes inconsistently). In 1957, the engine code did not contain a serial number (or a date code). From 1957 until an "official" VIN was used, so the Vehicle Serial Number was the only useful title/registration code/identifier.
