When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways (NGR) and Central South African Railways (CSAR)) were united under a single administration to control and administer the railways, ports and harbours of the Union.
The rest of the CGR's 6th Class locomotives, together with the Classes 6-L1 to 6-L3 locomotives which had been inherited by the CSAR from the Oranje-Vrijstaat Gouwerment-Spoorwegen (OVGS) via the Imperial Military Railways (IMR), were grouped into thirteen more sub-classes by the SAR.