contact the Mercury Marine Tech at Mercruiser. The number is: 920 929 5040. I needed the part number for my Horizon engine. Have your serial number for the engine, and he will look it up. For my model there is a subsequent alternator since installation. He pointed this out providing the newer part number. In fact there were two models used. He sent photos of each to match up to the one on the boat. For each model he gave me the part number. Very helpful. Best regards, Twin Engine
