Notes: Standard Rotation; Optional Non-Thermal Fan Clutch; Fan Mounting Holes are 5/16 In. Part Type: Engine Cooling Fan Clutch. Standard or Reverse Rotation Non-Thermal Fan Clutch. Fan Clutch. 1988 Chevrolet C1500 Engine: 4.3L V6; Standard Rotation; Optional Non-Thermal Fan Clutch; Fan Mounting Holes are 5/16 In.;.