In 1939, 15 FEF-2 class 4-8-4s, numbers 820 through 834, were acquired. They shared a family resemblance to the big Challengers and Big Boys. The FEF-2s were built as coal burners with single exhaust stacks, drop coupler pilots and “centipede” tenders that carried 25 tons of coal and 23,500 gallons of water.

When they were rebuilt, they received double or triple exhaust stacks. During the traffic crunch of World War II, ten more 4-8-4's of class FEF-3, numbers 835 through 844, were acquired. The FEF-3 boiler was slightly longer than the FEF-2; plus, the FEF-3 featured double exhaust stacks, cast pilots and cabinets on the tender. Within six months of delivery, they were fitted with “elephant ear” smoke deflectors. Several FEF-3s also received triple exhaust stacks.

All of the 4-8-4s were converted to burn oil after the Second World War. They also wore two-tone gray paint from April 1946 until the mid-1950s. While UP streamliners were all diesel powered, the FEFs worked the secondary trains such as the Pony Express and Overland as well as mail trains. At the time, those trains were usually quite long and consisted of heavyweight cars, requiring all of the power the FEFs could deliver.

Rebuilt in 1946, FEF-3 837 was changed to an oil burner with triple stack, red signal light, feedwater heater and two-tone gray paint which lasted until the mid-1950s.

Features:

• Smoke lifters
  
• Oil burner
  
• Triple smokestack
  
• Swing coupler pocket
  
• Feedwater heater
  
• Single generator
  
• ATS cabinet on the tender
• See-through running boards with safety tread pattern
• Eccentric cranks operating on both sides in the correct direction
• Opening cab doors and hatch
• Minimum radius: 22”
• Factory-installed DCC soundboard and speaker in the tender
• Operates in both DC and DCC