All 1966 Ford Mustangs rolled off the Ford assembly lines complete with a Vehicle Identification Number (VIN) and a Data Plate. The VIN is stamped atop the driver's side engine bay wall. The Mustang data plate, which is riveted on the driver's side doorjamb, also contains the VIN. These two items provide all the details of how the Mustang was first manufactured — the Mustang's DNA if you will.