By upgrading the G12 with the new 645 series engine, the G22 was born, which was again built in a wide variety of variants for customers in the first, second and third worlds. Using a non-turbocharged engine has increased reliability and simplified maintenance. The locomotives were available with different gauges and with two- and three-axle bogies. The six-axle variants were available with either the “C” model designation with six traction motors or the “4” model designation with the (A1A)(A1A) wheel arrangement. Steam heating was available as an option. In later variants, the modular electronics of the “Dash 2” were installed, these can be recognized by the suffix “-2”.

The Brazilian Estrada de Ferro Vitória a Minas required more powerful diesel locomotives than the previously used EMD G16U at the end of the 1960s. So far, the ore trains with up to 150 cars have been pulled by two or four G16Us and there are plans to pull them with just one or two single-engined locomotives in the future. At the time, EMD's most powerful single-engined diesel locomotive available was the SD45 with the 3,600 hp 20-cylinder. However, it turned out to be problematic for use with the EFVM that due to the meter gauge used, the traction motors were smaller and therefore not powerful enough to implement the full engine power with a total of six traction motors. 

The solution was to use four-axle bogies similar to those used on the DD35 or DDA40X, so that each traction motor only had to provide an eighth of the total power. This resulted in the DDM45, of which a total of 83 were delivered to the EFVM from 1970 onwards. The type designation was made up of the wheel arrangement DD, M for a different track gauge and the SD45 as the basic model. The locomotives could each replace two of their predecessors and were more economical to use. They usually drove double-headed with 160 ore wagons with a total weight of 12,000 tons or triple-headed with 240 wagons and 18,000 tons. In terms of performance, they were surpassed from 1991 by the newly arrived General Electric Dash 8 with 4,000 hp. Shortly before, two examples had been equipped with more modern Caterpillar four-stroke engines, but due to the high costs of the conversion, no further ones were converted and the two were later dismantled. Some engines came to the private FCA after the turn of the millennium, but were returned to the EFVM in 2008.

While the G22 was delivered without a turbocharger for easy maintenance, the GT22 received a turbocharger and correspondingly higher output. Here, too, different variants were created with four or six traction motors, different track gauges and with or without train heating. On request, the locomotive was designed to be particularly light. Soon the more modern generation of electronics was installed, called “Dash 2” by EMD. Individual variants, such as the GT22HW-2, were only built for a single customer. In this case it was the Yugoslav Railways, which ran the locomotives as the series 645.

The U9B and U12B were among the first and also the lightest models in the Universal series. The shorter end also formed a high hood and thus limited the view of the track, but there were full driver's desks in both directions. The U9B was powered by a 990 hp inline six-cylinder engine that drove four traction motors with a total of 900 hp. The U12B used a V8 that produced 1,320 hp and supplied the traction motors with a total of 1,200 hp. When the specifications of the UIC for calculating the power changed and the U12B now apparently provided more power, it was renamed the U13B in 1960 for marketing reasons. The six-axle U9C, U12C and U13C were offered for routes with lower axle loads. 

All three variants were purchased by a total of five operators in Brazil. Among them were ten locomotives for the Companhia Paulista Estradas, which were built for a gauge of 5 feet 3 inches. A total of 109 more went to other railways with a meter gauge network. Ten U13Bs went to Cuba and were the only examples of these types built for standard gauge. The largest order came from South African Railways for 45 U12Bs in Cape Gauge or 3 feet 6 inches. Similar to the electric locomotives, they were first designated as 1DE before they were redesignated as class 31-000. They were actually procured for shunting, but then spent most of their time in service on the line, usually in pairs of two. They were relegated to the shunting role in the 1980s and some survived into the 1990s. The short hood of two locomotives was subsequently converted into a low version and these engines were still a long way from being phased out after 2010.

General Electric has been offering the U20C since 1964, which was primarily intended for use in developing countries with its low axle load and suitability for a wide variety of track gauges. According to GE's scheme, the model designation stands for the Universal Series, an output of 2,000 hp and three axles per bogie. To achieve the required power at low weight, the 7FDL with eight cylinders and two turbochargers was used. On request, the engine could also be ordered with twelve cylinders. The locomotive could be built for gauges between three feet (914 mm) and the Indian broad gauge with 1,676 mm.

The more than 1,000 machines were built in the USA, Brazil, Indonesia, South Africa and Germany. Several hundred were delivered to Brazil with a gauge of 1,000 or 1,600 mm. Several hundred also went to African customers. The largest numbers came to South Africa with 190, 114 to Mozambique and 83 to Zambia. Others went to Pakistan, Argentina, Bolivia, Colombia, Jordan and Turkey.

The U20C of the Indonesian KAI have a special position. They received a cab with a wide nose and slanted front end, manufactured by UGL Rail in Australia. The first twelve CC203 were delivered to Indonesia by GE from the USA starting in 1995 and 29 more were built directly by PT GE Lokomotif Indonesia. A locomotive was built for the Philippines in 2000 and has been in service in Australia since 2007. From 2006 followed 30 CC204, which are designated by GE as C20EMP and have a 2,150 hp engine with computer-aided control.

Chilean operator SQM's U20C in April 2012 with a nitrate train at Barriles

Kabelleger / David Gubler

In Indonesia, the locomotives were initially used mainly for express trains of the “Argo” brand. With the introduction of newer locomotives, they were increasingly used in front of local and freight trains. Six belong to a private operator and haul pulp trains. Four CC203s have now been retired. Since the introduction of the CC206, the CC204 has also increasingly had to pull freight trains.

The U26C is a six-axle variant of the Universal Series designed for Cape and meter gauge. Despite the "26" in the designation, most of the machines were 2,750 hp, with only those delivered to Kenya having just 2,610 hp. The 255 South African locomotives of classes 34-000, 34-400, 34-500 and 34-900 make up the largest part. Two of the New Zealand locomotives were rebuilt in 1993 and 2006 to class DXR with 3,000 hp.