Holley is pleased to offer simple, clean, cost effective solutions that solve the accessory drive challenges encountered when swapping a GM LS engine into a muscle car, truck, hot rod or other vehicle. These brackets were designed to deliver a factory style appearance, correct belt alignment and factory stability. NOTE: This bracket REQUIRES an installation kit for assembly (Part 21-1, 21-2, OR 21-3, see Fitment Guide below for the correct installation kit for your application). Holley's kits supply the required brackets and hardware needed for installation, but allow you to choose the source for supplemental accessories and components that are often already on the donor engine or host vehicle. Whether sourcing from the salvage yard, the local auto parts store, your GM parts dealer, or Holley, you pick the accessories that match your needs and budget! A Fitment And Required Components Guide helps you locate and source components and provides other notes and helpful hints. Three easy steps will get you going. Step one is to determine your belt alignment based on your crank pulley position on the engine you have. Step two is to choose the Holley accessory drive brackets that you need (A/C, Alt & P/S or both). Step three is to see which Holley installation kit your set-up requires to line up your accessories with your crank pulley position. An application specific installation kit (part # 21-1, 21-2, or 21-3) is REQUIRED for most applications. Replacement hardware kit is 97-171.