Tips on how to identify your Mercruiser Sterndrive

Alpha Gen 1 pre 1990, Serial number 0D469858 and below, the impeller pump is mounted in the drive, the water pump housing is made of plastic (see part RM46-00048), and the trim & tilt rams are held on with nuts.

Alpha Gen 2 1991 - UP, Serial number 0D469859 - Up, the impeller pump is mounted in the drive, the pump housing is made of stainless steel (see part RM46-46502), and the trim & tilt rams are held on by e clips.

Bravo 1 Drive, the impeller pump is mounted on the engine, single propeller, the prop shaft has 15 splines, and they use an anode behind the prop.

Bravo 2 Drive, are used on larger boats, the impeller pump is mounted on the engine, single propeller, the prop shaft has 19 splines and DO NOT use the anode behind the prop.

Bravo 3 Drive, are duo prop, 2004 - Up versions use an anode on the end of the prop shaft, and 2 cavitation plate anodes.