Stand behind the motor and on the left side where the cylinder head meets the block on the deck surface there is a number stamped in the deck. If you call us and give us that number we can tell you when it was built and who it was built for along with the components we used. If the motor is less than 10 years old. We use a coded prefix because someone in Ocala and also someone in south Florida is putting our style covers on junk yard motors and selling them to people as motors that we built. So please if you have any questions call 321-508-5316.