For heavy passenger service on their metre-gauge network laid with light rails, the Rio Grande do Sul operated a total of 42 4-8-4 locomotives built in 1945 and 1946. Although heavy for non-articulated locomotives on a metre-gauge line, they were among the smallest locomotives of this wheel arrangement. They had a twelve-wheel tender with a large coal capacity and a large firebox with arch tubes and thermic syphons.

The first batch of 27 locomotives, numbered 1001 to 1027, was built in 1945 by ALCO-Schenectady. 15 more were built by the Montreal Locomotive Works in 1946 and numbered 1028 to 1042. They had a higher boiler pressure of 245 instead of 235 psi and were also 1,000 pounds heavier. They became surplus in Brazil as early as in the mid-fifties and some were sold to the Bolivian State Railway, where they were used until 1980.