The casting number 3970010 indicates a 350 cubic inch Chevrolet small-block engine block. However,
the casting number alone doesn't tell you the year. That information is contained in the partial VIN-like number stamped on the block, in your case, 12W297191.
The "12W" portion is the key. This indicates a 1972 production date. The "W" is the tenth digit, representing the assembly plant and week of manufacture during the 1972 model year.
