http://en.wikipedia.org/wiki/Vehicle_Identification_Number1981 would be the date that the acronym VIN had a standardized meaning/location/format in the USA.
You'll get used to VIN being used here and being "flexibly" defined - you'll never get your wish regarding this peeve. By the way, I have seen titles from the same state, in the same mid-50s year, where the engine number was used on one truck and the tag/vehicle number used on another truck.
