During the 1950s and 60s they were manufactured by EMD, GMD and their representatives around the world Clyde Engeneering, HoHAB and Henschel Altogether 1126 G12 and 373 G8, being low-cost machines and simplified enough to have a reasonably low operating cost by company standards. time. They used the 12-567C engine in the case of the G12 and 8-567C in the G8, engines that were unsophisticated, but that met the demand very well and were reliable. All of this at a high fuel consumption when compared to European machines at the time, however, European manufacturers were not yet in a position to export machines immediately. The cost of fuel was not a problem, because even though it was imported in some countries, diesel oil and all other petroleum products were cheap, even more when compared to steam traction, either wood, coal or fuel oil. His project followed the same conception of the General Purpose (GP) series that was already quite successful in the USA since 1947 with the launch of GP7. They would be bidirectional machines, adaptable to trunk lines or branches, of cheap and fast construction, sacrificing aesthetics and above all, that were as functional as possible.
 
Units were manufactured from 71 tonnes to 90 metric tonnes, in B-B, A1A-A1A and even C-C, with or without dynamic brake. There were options for Flexicoil or Bloomberg tricks. They were sold to the following countries: South Africa, Argentina, Australia, Brazil, Canada, Ceylon (Sri Lanka), Chile, South Korea, Egypt, Holland, Hong Kong, Indonesia, Iran, Israel, Liberia, Mexico, Norway, New Zealand, Sweden, Venezuela and Taiwan. It has become one of the most successful export machines of all time, being present on five continents. Currently, some of its units continue to operate, although the vast majority of them were paralyzed in the 1980s with the introduction of the EMD 645 engines and more modern machines such as the G22 (direct replacement), G26 (G16 replacement), GT22, and already in the 1980s the JT42 and JT46 combined with the improvement of the technical conditions of the railroads, which previously needed to operate only machines such as the G12, made it possible to use larger machines or even normal machines for domestic use, this was a blow to the G12 , whose engine design was not focused on economy, but on durability and ease of maintenance. Countries like New Zealand stopped almost all of their units, cutting them off and today, few are left in the hands of conservation organizations.