Replacement "squareback" style alternator. These work with the 1970 & later style "dual field" electronic regulators. They can also be used with the '69 and earlier single field "points" type regulator if one field is connected to ground. These may have either a dual or single pulley. If you are using them with a single belt setup, only the pulley closest to the alternator is used. They work great with our brackets, belts, and bolt & spacer kits listed above. Some details in the appearance of the actual part may vary slightly from the picture, especially the pulley type and color.