Aluminum 5 piece serpentine pulley set to convert a standard V-belt system to the newer style serpentine set-up. Will fit 1965-1990 Oldsmobile V-8 engines and will work with either long or short water pumps. DMR-30180 a 1/2" spacer kit will be needed to adapt short water pump to fit in place of longer A/C pump. Great for show application and will help eliminate throwing belts under high RPM applications. Comes with a black hard coat finish to prevent the belt from wearing the pulleys as can happen with normal aluminum pulley sets. Includes alternator, power steering, idler pulley, idler pulley bracket, crankshaft and water pump pulleys. The water pump pulley has a "V" groove at the back to drive the air conditioner. Uses a normal clockwise rotation water pump. Available in standard drive or underdrive sets. Crankshaft in the underdrive sets are approximately 20% smaller to drive the rest of the pulleys approximately 20% slower. Will save HP as the tension on a serpentine set is about 1/2 that of a "V" belt set.