NEW ALTERNATOR FITS MERCRUISER 120 GM 2.5L 3-WIRE 1977-1989 20104 1100186 1102938 1102939 1103113 11031141103193 100% NEW and Made with the Highest Quality Components Available Full One Year Warranty Computer tested for consistent Quality and unsurpassed reliability Alternator - Voltage: 12V Amperage: 110 Amps Source: Aftermarket