The South African Railways Class of 1974 is a diesel-electric locomotive. Between December 1974 and July 1976, the South African Railways placed one hundred Class General Motors Electro-Motive Division type GT26MC diesel-electric locomotives in service. Manufacturer The Class type GT26MC diesel-electric locomotive was designed by General Motors Electro-Motive Division and built for the South African Railways (SAR) by General Motors South Africa (GMSA) in Port Elizabeth. One hundred locomotives were delivered between December 1974 and July 1976, numbered in the range from to . Distinguishing features Of the GM-EMD Class 34 family of locomotives, Classes and units are visually indistinguishable from one another, but they can be distinguished from the Class by the thicker fishbelly shaped sills on their left hand sides compared to the straight sill on the left hand side of the Class . Rebuilding and modification Class 39-000 The Class 39-000 type GT26CU-3 diesel-electric locomotives were to be rebuilt from Class , and locomotives. The project commenced in 2005, using suitable frames from wrecked locomotives. Rebuilding was done at the Transwerk shops in Bloemfontein between 2006 and 2008. It was intended to produce one hundred Class locomotives but in spite of the technical success of the project, rebuilding was halted after completing the first five locomotives due to higher than anticipated cost. It was decided, instead of rebuilding old locomotives, to continue the program by building fifty new Class locomotives from imported and locally produced components. Three Class locomotives, numbers , and , were rebuilt to Class before the rebuilding project was halted. Traction motor upgrade In 2010, an upgrading project commenced at the Koedoespoort Transnet Rail Engineering shops to upgrade Class locomotives by, amongst other modifications, replacing the GM-EMD D29B with GM-EMD D31 traction motors, thereby improving their performance to the standard of the Class . Locomotives that are known to have undergone this upgrade are annotated "D31 TM" in the "Leased, rebuilt or sold to" column in the table. Service South African Railways In SAR, Spoornet and Transnet Freight Rail (TFR) service, the Class worked on most mainlines and some unelectrified branch lines in the central, eastern, northern and northeastern parts of South Africa. National Railways of Zimbabwe From at least 1988 until at least 1992, the National Railways of Zimbabwe (NRZ) hired type GT26MC Class locomotives from the SAR and later Spoornet. Locomotives which were observed to be working on the NRZ between April