Union Pacific Challenger 3977, at North Platte, Nebraska. According to the information board, Challenger 3977 was built in 1943 and worked freight and passenger service until retirement in 1961. This locomotive is 121 ft 10 inches long, 16 ft 4 inches tall and 11 ft 6 inches wide. The tender has a capacity of 28 ton of coal, or 5945 gallons of oil and 25,000 gallons of water. Total loaded weight is 1,069,800 lbs. Officially this is a 4-6-6-4 Challenger type Mallet.