The serial number tag is located to the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Found in between the thumb screws above the steering tube. By moving into your email handle you agree to receive marketing messages from Yamaha Outboards. Chances are you'll unsubscribe at any time. https://yamaha-outboard-motors30524.blogzet.com/top-boat-marine-temperature-switch-secrets-51656764