In 1906, North British built 34 2-6-2T tank locomotives of the class 8A for the Ferrocarril del Sud, or Buenos Aires Great Southern. These locomotives had an oil fired boiler with Belpaire firebox, outside cylinders and inside Stephenson valve gear. With drivers of 62 inches and relatively small water tanks of 1,200 gallons, they were mainly intended for suburban service, but delivered good performances with almost all train types if needed. At the beginning, they were numbered 394 to 415 and 456 to 467. From 1913, they carried numbers between 3321 and 3354. Over the years, the shops of the BAGS rebuilt 26 of the 34 locomotives with superheated boilers.