In 1913, Robert Stephenson & Co. delivered ten 2-6-2T tank locomotives to the Ferrocarril del Sud de Buenos Aires which had the works numbers 3471 to 3480. The specifications came from Messrs. Livesey, Son & Henderson. North British delivered 31 more of the same design in the same and the following year. These carried the works numbers 20186 to 20216. They were designated clase 8C and carried the numbers 3451 to 3490.
Essentially, they were the tank version of the 2-6-0 clase 7D built by Beyer-Peacock in 1912. Like these, they were oil-fired and superheated. With the same driver diameter of 5 ft 8 in, they had the largest wheels of any 2-6-2T of the BAGS. The majority of the class was used in suburban service around Buenos Aires. Some were used in Bahia Blanca and Tandil.