Mercury - Marine Alternator 12-Volt / 51 Amp Series Corrosion-Resistant Finish 8M6007494. Overview.. There's a certain comfort that comes from knowing your electrical system is ready for whatever the day brings. Whether you're easing away from the dock before sunrise or running your spread of electronics offshore, a dependable alternator gives you the quiet confidence that everything will keep humming along. That's the feeling you get with Mercury Marine part number 8M6007494. It's the kind of p