The S series of 6 phase alternators offers incredible low RPM output in a compact and durable package. Highly efficient, these units use less horsepower than conventional 3 phase alternators. 12 diodes, twin rectifier plates and outstanding airflow ensure long service life, even in severe conditions. This unit is specially designed to replace CS130 alternators with 6.15 inch center-to-center distance bolt patterns, as used by several aftermarket accessory drive manufacturers. This unit includes a specially machined March performance 6 groove serpentine pulley, fan, and decorative cover already custom fitted to the alternator, and features a simple one-wire hookup. The 1.75 inch diameter pulley on this unit is ideal for maximizing amperage capability at engine idle RPM. Be sure to calculate your pulley ratio for high RPM or racing applications to ensure the alternator is not over-spun when at high engine RPM.