1967 GMC K25/K2500 Pickup Engine: 4.1L L6; Standard Rotation; Optional Non-Thermal Fan Clutch;. 1967 GMC K25/K2500 Pickup Engine: 4.6L V8; Standard Rotation; Optional Non-Thermal Fan Clutch;. 1967 GMC K25/K2500 Pickup Engine: 4.8L L6; Standard Rotation; Optional Non-Thermal Fan Clutch;.