The 0-80555C is a Model 4175 designed to fit GM spread bore passenger car and light truck applications. It is not compatible with Ford or Chrysler Spread bore applications. The 0-80555C is not recommended for any RV applications. The 0-80555Sis not designed to pass any emission laws. The 0-80555Sis to be used only for competition/off road vehicles or vehicles not required to comply with any exhaust emissions standards. A carburetor spacer could be required to clear certain components on stock applications