Flash and Tish are correct. Should be on the top of the frame on the driver's side by the steering box and on a stamp located on the firewall. A lot of the times the firewall stamp is missing or has been taken off if the car has been street rodded.
Previous posted picture of my father's 1940 Ford Convertible.
Also, not to hijack, but we need a '40 Deluxe hood if anyone has one they wanna get rid of.
Chris