THESE 3 PC. SETS INCREASE HORSEPOWER ON ALL SERPENTINE BELT 3.8L V6. THE SMALLER DIAMETER CRANKSHAFT PULLEY COMBINED WITH THE ORVERSIZE ALTERNATOR AND WATER PUMP PULLEY RESULT IN MEASUREABLE PERFORMANCE IMPROVEMENT.THESE PULLEYS ARE EASILY INSTALLED WITH REGULAR HAND TOOLS. THIS IS A 25% TOTAL UNDERDRIVE AND PREVENTS BELT SLIPPAGE. THEY ARE 6061-T6 BILLET ALUMINUM EXPERTLY MACHINED AND HAS A BLACK PROTECTIVE POWDER COATING. PULLEY SET FITS THE THUNDERBIRD SC 1989-95. COMES IN BLACK AS PICTURED. Sorry about the high price, but the manufacturer has recently increased it over 50%! We are still working on the aluminum set of these pulleys.