Most States if not all used the engine serial number for their title identification numbers up until about 1955. By 1957 you could no longer use a Chevrolet engine for that purpose as they stopped stamping unit numbers on the block, so you had to use the Body/Chassis numbers.
Lots of cars have legally gone through the process of having the engine number on their title switched to the Body/Chassis number by their local DMV so this adds to the confusion.
Mike B
