This voltage regulator is compatible with the following engine models: FC540V, FD501D, FD590V, KAF620, FC420V, FD440V, FD620D, FD661D, FD671D, FD711D, FD750D, FD791D, FE290D, FE350D, FE400D, FD501V, KAF540 (Mule 2010, 2020, 2030), KAF620 (Mule 2500, 2510, 2520), and KAF300 series (Mule 500, 520, 550 variants).It is also compatible with part numbers 21066-2056, 21066-2070, B3-08B302, B3-08B391, B3-11B591, and C3-12K501.Includes one voltage regulator per package.