"Stand alone" type, 4 terminal starter solenoid used on various Indmar applications.  This solenoid is also designed to be used in 3 terminal applications.

The following connections are used for a 3 terminal application:

1 of the larger terminals is connected to the battery lead

1 of the larger terminals is connected to the starter lead

The 3rd smaller diameter wire is connected to the terminal marked "S" on the solenoid for the switch

The 4th terminal is not used and left unconnected