We rate our jack plates based on the horsepower they support for motors built after 1978. For smaller clamp-on engines less than 40 HP we have our mini jack plates. For smaller engines less than 40 HP that are not clamp on style and have the standard bolt pattern you can use the 40 HP and up jack plates. The motor manufacturers do not necessarily always use the standard bolt pattern in their motor brackets for engines 40 HP and less so we recommend double checking this before ordering.