Between April 1973 and November 1974, the South African Railways placed one hundred Class 34-400 General Electric type U26C diesel-electric locomotives in service.

At some stage during the mid-1980s, all Class 34-000, 34-400 and 34-500 locomotives had saddle filters installed across the long hood, mounted just to the rear of the screens behind the cab on the sides.

[7] To be usable on the iron ore line, Class 34-400 units which ended up working there were modified to a similar fuel capacity.

On some of the first locomotives to be so modified, externally visible evidence of the modification is a raised middle portion of the long hood.

GE Class 34-400s work on most mainlines and some branch lines in the central, western, southern and southeastern parts of the country.

[1][3][10][11] Eleven Class 34-400s were leased to the Kenya Railways for some years, regauged to 1,000 mm (3 ft 3+3⁄8 in) and renumbered in the range from 9501 to 9511.

In the 1990s many of the Class 34-400 units began to be repainted in the Spoornet orange livery with a yellow and blue chevron pattern on the buffer beams.