It is an original Ford toolkit wrench...the small open ends came in 7/16X1/2 and 9/16X5/8, no sense of size there. Again hard to judge, bur looks like the slimmer type put in kits 1940-1948. Heated and bent for some specific job by a previous owner, not made thus by Ford.
Specialized shop tools for early Fords were not marked that way...this is certainly a toolkit open end bent after it left the factory.
If the bent end is 9/16...well, that's the way I would want to bend one if I were trying to remove a flathead oil pressure sender in the car!