Between May 1981 and 1982 the South African Railways placed one hundred Class 37-000 EMD GT26M2C diesel-electric locomotives in service. It is a more powerful version of the EMD Class 34-200, 34-600 and 34-800, designed by Electro-Motive Diesel and built by General Motors South Africa in Port Elizabeth. They were numbered in the range from 37-001 to 37-100. In 2008 one of them, no. 37-010, was rebuilt to Class 39 prototype no. 39-251 that was tested but rejected by Transnet and later reported as sold to RRL.
See also the Wikipedia article on the South African Class 37-000.