This is an aluminum pulley that we custom machined for an old Ford industrial work truck that has a 3408 Caterpillar V8 diesel engine in it. The original pulley was a two piece setup made out of steel. The original setup kept breaking the bolts and chucking the fan into the radiator causing radiator leaks and engine overheating. After installed it never broke the bolts again and the whole engine seemed to run smoother as the fan was spinning smooth without any vibration. We later had the pulley hard anodized in black to protect the v-grooves from getting worn by the belts. Motor Mission Machine & Radiator 5435 Desert Point Dr. Las Vegas, Nv. 89118 Phone: (702) 649-2366 or (702) 649-0648 Fax: (702) 649-4133 www.MotorMission.com Facebook.com/MotorMission