The Elite series 250 amp alternator offers great output at idle RPM and excellent durability in a direct-bolt-in package. 6 phase technology, combined with massive twin rectifier assemblies and 12 diodes makes these alternators totally durable for daily use, while still maintaining great output at low RPM. These alternators will make 180 amps at engine idle speeds with a full 250 amp output at cruising speeds. This unit comes with an OEM diameter pulley, making it perfect for high RPM and racing use. NOTE: This unit may require a rectangle to oval adapter harness if your vehicle was equipped with the CS144 Heavy duty charging option from the factory. (this is not common) Ask a MechMan associate for assistance if you are unsure!