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 320 amp high output unit is specially designed to replace CS130 and 10/12SI alternators with 6.61 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. A single wire on the provided pigtail gets connected to any ignition switched 12V+ source to turn the alternator on and off with the ignition switch. Simply run a properly sized positive and ground cable from the alternator to the terminals of the battery and the alternator will work perfectly, regardless of what kind of wiring harness you have. The 1.75 inch diameter pulley 140+ amps as just 800 engine idle RPM with a 7" crankshaft pulley. Due to the high pulley ratio necessary for good charging at engine idle RPM, this unit is not recommended for use over 6,000 engine RPM.