In 1931, the Western Pacific ordered the first six articulated 2-8-8-2 locomotives from Baldwin which had to haul the Pacific Fruit Express through the Feather River Canyon. They had four equal cylinders of 26 by 32 inches and relatively large drivers with a diameter of 63 inches. This resulted in a starting tractive effort of 137,000 pounds, and a trailing truck booster added 13,900 pounds to that. Each locomotive alone weighed 665,000 pounds or 1,073,000 pounds with tender. Although they were fired with oil, their grate measured 145 square feet. The firebox had a surface of 739 square feet, what included 217 in five thermic syphons and 155 in the combustion chamber. 

The first six locomotives were numbered 251 to 256. Two of them had a Worthington No. 6 feed water heater, while the other four had an Elesco Type K-60. They said that the closed-system Elesco models were not suited for feed water of bad quality, while the open-system Worthington models had less problems with that. On the one percent grade in Feather River canyon, they managed to haul fruit trains with 65 to 74 cars with a speed of 18 to 25 mph. 

Four more were delivered in 1938 which received the numbers 257 to 260. They had steel locomotive beds with integrally cast cylinders and closed-system Coffin C-2 feed water heaters. They had only two instead of three thermic syphons in the firebox itself, but still had the two smaller ones in the combustion chamber. Soon the boiler pressure of all locomotives was raised from 235 to 250 psi. Although they delivered good performances, the Western Pacific was one of the faster American railroads to dieselize. So they were retired in 1951 after they had been replaced by four-unit EMD diesel locomotives.