The serial number tag is located about the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Found amongst the thumb screws above the steering tube. The good thing is, PartsVu provides a wealth of resources that can assist you find the Mercury outboard parts you need to keep https://yamaha-outboard-motors-go63848.ka-blogs.com/90019818/rumored-buzz-on-honda-bf15d-outboard-motor