Clutch Masters 05-07 Dodge Ram 2500/3500 5.9L 6spd FX1200 Race Twin Disc Clutch w/ Steel FlywheelThe 1200 series is a larger diameter assembly, which is designed for high torque output applications. The 1200 Series has a higher holding capacity, and designed for excessive towing on truck applications. The 1200 series Twin disc will accept one sprung disc creating a slightly smoother engagement compared to two rigid discs