The 5.5" and smaller Tilton clutches require a 38mm contact diameter clutch release bearing on the Annular piston. The Taylor Race Engineering piston cup allows conversion of the stock Van Diemen piston to utilize the 38mm contact bearing PN 362-008, or if using a Quartermaster clutch, use a 44mm contact bearing PN 362-031.Conversion Kit works on the 1999/2006 Van Diemen. Note: Some minor modifications required. Instructions included with Piston Adapter kit.