In 1930, the South African Railways placed six redesigned Class 16DA steam locomotives with a 4-6-2 Pacific type wheel arrangement in passenger train service.

[1][2] In an attempt to improve the steaming properties of further orders of Class 16DA locomotives, A.G. Watson, who had succeeded Colonel Collins as CME in 1929, designed a boiler of the Wootten type.

Watson was a firm believer in large firegrates with enlarged blast pipe caps to give a reasonably low burning rate of fuel per unit of grate area, which improved boiler efficiency and reduced the emission of sparks and partially burnt fuel.

[1][3][4] This boiler and firebox was installed on these final six Class 16DA locomotives, numbered in the range from 874 to 879, which were built by Henschel and delivered in 1930.

This rotary poppet valve gear was driven from a single gearbox on the centre of the driving axle.

At the same time, their operating boiler pressure was raised to 205 pounds per square inch (1,410 kilopascals) to not have their tractive effort reduced by the larger coupled wheels.

[9] When new air-conditioned rolling stock was placed in service on the Union Limited and Union Express services between Cape Town and Johannesburg in 1939 to 1940, all the Class 16DA and Class 16E locomotives were transferred to Bloemfontein in the Free State.