The serial number tag is located on the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Positioned in between the thumb screws above the steering tube. This document contains many of Yamaha's valuable trademarks. It may also include trademarks belonging to other companies. Any references to other companies https://yamahaoutboardmotorsyamah00638.dgbloggers.com/37413463/used-mercury-outboard-motor-values-no-further-a-mystery