What is the "VIN" code you found?
Where did you find that code?
Is it the Engine Number?
ID plate in door jamb: "C51 232 then what looks like WJ0"
That code is typically called the Vehicle Number or Vehicle Serial Number.
That is an odd looking stamping = both the locations and sequence/contents do not look right
It does not match format or content for 1951 Chevrolet trucks Maybe someone else can help with the decode?