The serial number tag is found over the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, Positioned amongst the thumb screws above the steering tube. The good thing is, PartsVu includes a wealth of resources that will help you find the Mercury outboard parts you need to keep https://yamahaoutboardmotorscanad48924.kylieblog.com/37513202/detailed-notes-on-bf75-honda-outboard