The serial number tag is found to the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, located in between the thumb screws above the steering tube. Thankfully, PartsVu provides a prosperity of resources that can assist you find the Mercury outboard parts you need to keep the engine https://trentonhgebb.vidublog.com/35834900/the-smart-trick-of-yamaha-150-gph-that-nobody-is-discussing