One of the challenges with a Gen III Hemi swap is getting the factory alternator to work correctly. The factory ECU is required to control (excite) the Mopar factory alternator, but you may not want to use that ECU since it was designed for a production vehicle with security and other factory features (that make it tough to use in an engine swap on a vehicle that didn't come from the factory with the Gen III Hemi engine). This special alternator is for use with the factory Truck accessory drive system (2003 & Up 5.7L and 2011 & Up 6.4L Gen III Hemi engines), but is easy to wire and works without the factory ECU. Natural cast aluminum finish for a stock look that matches the other factory accessories.