These models were designed especially for common-carrier service. The 44-ton, at 88,000 pounds, was the biggest one-man locomotive possible under the 90,000 pounds (45-ton) rule of the 1937 diesel agreement protecting firemen's jobs.
With 400 horse-power, the 44-ton was produced between 1940 and 1956, with 334 produced in the United States, 9 in Canada and 5 in Mexico.
