In 1909 H.H. Vaughan would produce a Consolidation that should achieve more power with 24x32 inch cylinders, but thanks to 63 inch (1,600 mm) large driving wheels should have enough steam even at higher speeds. However, during the trial runs it became apparent that the boiler was still insufficient at higher speeds. This resulted in the production engines with a cylinder diameter of just 23.5 inches.

In the years 1909 to 1911 the production engines of the class N3a were built, in 1912 more of the class N3b and in 1913 finally the class N3c. Technically, the subclasses were almost identical, but they differed in the driver's cab. The N3b and N3c used all-weather driver's cabs, which were characterized by an additional vestibule.

Since the capacity of the boiler later still proved to be too low compared to the cylinders, the conversion to class N2a to c took place in the 1920s. The diameter of the cylinders was reduced to 23 inches and the area of the firebox increased at the expense of the tube heating area. A larger superheater was also used.

There were two different versions of the N2, which had different boilers with 141 and 165 tubes respectively. 40 locomotives were converted to oil firing by 1950. As early as 1946, 65 units were converted to the P1n class with the 2-8-2 wheel arrangement. Four remain today, of which 3512 has been lying at the bottom of Slocan Lake in British Columbia since 1947 after a barge carrying the locomotive capsized.