BBK 1619 Underdrive Pulley Kit For Ford Mustang 3.8L-V6 - 2 Pc CNC Machined Lightweight Aluminum - Crank And Alternator BBK is your Number One Aftermarket Performance Brand in the USA - American Designed and Built Installing this BBK Performance Underdrive Pulley is one of the Easiest Ways to Gain Approximately 8-10 Horsepower Direct Replacement Pulley Kit Requires a New Shorter Length Serpentine Belt and Will Not Affect Cooling or Charging of the Vehicle Premium Quality CNC Machined Lightweight Crank Pulley Kit Adds Great Looks and Performance 1 Pc Kit Includes Crank Pulley Only, All Hardware and Instructions for Simple Installation