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.