The serial number tag is located to the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Found among the thumb screws above the steering tube. Thankfully, PartsVu has a prosperity of resources to help you find the Mercury outboard parts you need to keep your engine running efficiently, https://josueajoty.frewwebs.com/37358849/the-smart-trick-of-yamaha-150-gph-that-nobody-is-discussing