ARCO NEW OEM Premium Replacement Alternator Fits: Late model Mercruiser, 12 Volt, 55 Amp, Internal regulator 2-inch mounting foot, Single groove pulley included. Replaces Part Numbers: MARINE POWER 1210-000 MERCURY 12449 MERCURY 78403A1 MERCURY 78403A2 MERCURY 817119A1 MERCURY 817119A4 MERCURY 92497A3 MERCURY 98555 MERCURY 98555A1