Difference between Holden H186 and H186 engines

The 186S motor was a sporty six introduced in the HR model and continued in the HK, HT and HG models. It replaced the X2 twin-carb motor in June 1967, and had revised inlet and exhaust manifolds and a modified air cleaner. Peak power was 108 kW at 4600 revs and maximum torque was 249 Nm at 2200 revs. It's not a super rare engine.