After the train weights on the Trans-Australian Railway had increased in the 1930s and the line was extended to include a branch to Port Pirie, the existing class G passenger locomotives reached their limits. Even the rebuilding of seven units with superheaters could not solve the problem, so that additional engines were necessary. Eight heavier locomotives were therefore ordered from Walkers Limited, which were again based on the New South Wales Government Railways class C36 built from 1925. The locomotives themselves were again taken over almost unchanged, but significantly heavier tenders with six axles were attached.

These locomotives were built by Walkers Limited of Maryborough, Queensland and were delivered in four months in early 1938. They were used on the Trans-Australian Express right from the start and replaced the previously used class Ga locomotives within a very short time. The main reason was that they covered the distance in ten hours less. During the major strikes in the coal industry in 1949, four locomotives were temporarily converted to oil firing. The introduction of the GM class diesel locomotives from 1951 ensured that the C class steam locomotives were retired at the same time as their predecessors. After the last one had served its purpose in 1957, all pieces fell victim to the scrap press. Only the large tenders survived into the 1980s, as they were used as water tanks for weed-killing trains.