South Carolina, Missouri, Ohio, Oklahoma, Texas and Utah require a "model year" when registering or titling your outboard motor. Yamaha, like Mercury Marine, has eliminated the "model year." Though Yamaha no longer associates a production year with a model, you'll know your outboard's model and the year in which your outboard was produced. All of the six states, with the exception of South Carolina -- which uses the "manufacture date" from the manufacturer's statement of origin -- accept the "year built" on the motor.
Look on your motor's registration. It may display the year and model, particularly if the motor was previously registered or titled in one of the six states that require a title and registration for outboard motors.
Look at the manufacturer's statement of origin (MSO). Yamaha provides an MSO with every new motor. Both the motor's model and the year built are part of this form.
Call the titling/registration office to familiarize yourself with the information needed. Look on the starboard (right) side of the motor bracket to find the MSO placard; both the model and year of production are stamped into the placard.