The serial number tag is found about the SWIVEL BRACKET (port or starboard); or, check the INSTRUCTION PLATE, located amongst the thumb screws above the steering tube. OMC Model Number Location The model and serial numbers of your vertical drive should be located to the engine model and serial number https://yamaha-outboard-motors-pa75173.blogofoto.com/68049139/not-known-details-about-marine-speed-boats