All the pulleys and brackets have to match so things line up correctly. All the brackets and pulleys are different for the V8 and the 6. They are also all different from A/C and non-A/C engines and '69 and older with the cast iron water pump and the the '70 and newer with the aluminum pump. Once you get a complete set, you can figure out what radiator you're going to need. The 6 and 8 had different hose connections and locations as well as the transition from '69 to '70.