All were built in American Locomotive Company's plant at Schenectady, New York and were numbered from 450 to 470 as delivered. The original C class were builders numbers 42439 & 42440 delivered in 1907, 46036-46038 in 1909, 47731 in 1910, and 49205-49206 in 1911. Sub-class C-1 consisted of builders numbers 50940 & 50941 built in 1912, and 52985-52986 & 53291 completed in 1913. Builders numbers 54568 through 54570 arrived in 1914 as sub-class C-2 with weight increased to 238,500 lb (108.2 tonnes).[2]
The last five Maine Central Pacifics were built with booster engines. Increasing cylinder diameter to 24 inches (610 mm) increased tractive effort to 36,500 lbf (162.4 kN) or 46,800 lbf (208.2 kN) with the booster. Enlarged tenders held 13 tons of coal and 9,100 US gal (34 m3) of water. Builders numbers 57885 through 57887 were delivered in 1917 with weight increased to 268,300 lb (121.7 tonnes). Building of new 4-6-2s was interrupted by World War I when the United States Railroad Administration (USRA) authorized construction of non-standard class O 4-6-0s because Maine Central Pacifics were so much smaller than USRA Light Pacifics. The final two class C engines were builders numbers 65554 and 65555 delivered in 1924.[3] Number 470 was preserved in Waterville, Maine after pulling the last Maine Central steam-powered train on 13 June 1954.[4]
