Once again these engines were used to experiment with a short boiler and Meyer expansion valve gear. Because the additional increase in size of the heating area could not be improved by installing extra tubes, two of each were rebuilt to 0-4-2 and 0-6-2 locomotives. Otherwise their construction was the same as the Class A II engines.
They were equipped with 2 T 4.2 and, following the rebuild, 2 T 5 tenders.
