1967 Chevrolet K20 Suburban Standard Rotation|Optional Non-Thermal Fan Clutch;. 1968 Chevrolet K20 Suburban Engine: 5.3L V8; Standard Rotation|Optional Non-Thermal Fan Clutch;. 1968 Chevrolet K20 Suburban Engine: 5.4L V8; Standard Rotation|Optional Non-Thermal Fan Clutch;.