Alternator Part Number AL9940X, 686696125922, 0120488294, 19020536 Key benefits Reliable charging performance for 12 volt systems rated at 45 amperes. Direct replacement for alternators specified by the listed part numbers, simplifying and inventory. Internal voltage regulator eliminates the need for an external regulator, reducing installation complexity. External fan design improves heat dissipation and helps maintain consistent output under load. Built with attention to quality control and industry standards to provide consistent, dependable operation. Main features Amperage: 45 A for stable charging of batteries and electrical accessories. B plus terminal thread: M81.25 for direct fit to compatible wiring and terminals. Polarity: Negative, compatible with standard negative ground systems. Regulator: Internal, integrated into the unit for simplified installation. Cooling: External fan to assist thermal management during prolonged use. Replacement capability: Replaces part numbers AL9940X, 686696125922, 0120488294, and 19020536 and meets the corresponding specifications. Function and performance This alternator provides consistent 45 amp charging output for automotive and equipment 12 volt electrical systems. The internal regulator controls charging voltage and the external fan aids cooling to maintain stable performance during normal and heavy electrical demand. Compatibility and fit Designed to be a dropin replacement where the electrical and mounting specifications match: 45 amp rating, M81.25 B plus terminal, negative polarity, and internal regulator configuration. Verify physical mounting and electrical connections against the listed part numbers before installation. Practical use scenarios a failed alternator in a vehicle that uses a 45 amp alternator with an M81.25 B plus terminal and negative ground to restore reliable charging and starting. Keep as a spare unit for fleet maintenance to reduce downtime when a charging system fault is diagnosed. Use during restoration or of older equipment where compatible alternator specifications match the listed part numbers. Technical summary Item: Alternator Part numbers replaced: AL9940X, 686696125922, 0120488294, 19020536 Amperage: 45 A B plus terminal: M81.25 Fan: External Polarity: Negative Regulator: Internal Confirm compatibility with the vehicle or equipment by matching these specifications and part numbers prior to or installation.