That's the serial numger not the casting number. Look by the fuel pump.

The date code is above the starter. A-L = month, next # is the day and the next is the year ie; D 13 6= April 13, 1956.

Check the left margin engine ID list.

Good luck. \:\)

John M., I.I. #3370

"There are no shortcuts to any place worth going". -Anon