In 1950, the Vehicle Serial Number is on the cab (between the hinges on the driver's side) and the Engine Serial Number is pressed into the block to the rear of the distributor.
There is/was no true VIN.
Either of the above codes could have been used for titling and/or for registration.
Unfortunately, the engine code was often used. If your engine got changed, you are SOL, unless someone put the original engine code on the replacement engine.