[blucar]

A serial/VIN number plate that is affixed to a door jamb,sill, etc., on a pre 48 Ford is a dead giveaway that it is an "assigned number" put there by some state.
If you can't find a number stamped into the frame adjacent to the steering gears you will have to pull the body off of the frame so you can see the secondary serial number location which is in the area of the rear frame cross-member, on the left frame rail.