The serial number tag is situated around the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Found in between the thumb screws above the steering tube. This document is made up of many of Yamaha's valuable trademarks. It could also comprise trademarks belonging to other companies. Any references https://yamaha-outboard-motors-fo50593.snack-blog.com/36934520/not-known-details-about-40-hp-outboard-motor-comparison