1987-1991 GMC R3500 7.4L V8. 1987-1991 GMC R3500 5.7L V8. 1987-1988 GMC R3500 4.8L 6 Cyl. Notes: Engine Cooling Fan Clutch -- Clockwise (Standard) Rotation; Thermal Fan Clutch; Severe Duty. Enhanced fin design for maximum heat dissipation, as well as, reduced fan noise and vibration during acceleration or cruising.
