BBK 1603 Underdrive Pulley Kit for GM Truck 4.3/5.0/5.7L - 3 Piece CNC Machined Aluminum BBK is your Number One Aftermarket Performance Brand in the USA - American Designed and Built Installing a Set of BBK Performance Underdrive Pulleys is one of the Easiest Ways to Gain Approximately 8-10 Horsepower Direct Replacement Pulley Kit Re Uses Existing Serpentine Belt and Will Not Affect Cooling or Charging of the Vehicle Premium Quality CNC Machined Lightweight Billet Aluminum Pulley Kit Add Great Looks and Performance 3 Pc Kit Includes Crank, Water Pump and Alternator Pulleys and all Hardware and Instructions for Simple Installation