1988 GMC R2500 Suburban Engine: 5.7L V8; Reverse Rotation; Optional Duty Thermal Fan Clutch; Fan Mounting Holes are 10 mm.;. Part Type: Engine Cooling Fan Clutch. 1988 GMC R2500 Suburban Engine: 7.4L V8; Reverse Rotation; Severe Duty Thermal Fan Clutch; Fan Mounting Holes are 10 mm.;.