The Santa Fe's 3800-class 2-10-2s numbered 141 locomotives delivered by Baldwin from 1919 through 1927. They had 63-inch drivers, 30x32-inch cylinders and a boiler pressure of 220 p.s.i. With a locomotive weight of 138 tons, they developed a hefty 85,000 pounds of tractive effort. They had 5087 square feet of evaporative heating surface and 1345 square feet of superheater surface, and a grate area of 85 square feet.

The 2-10-2 is known as the Santa Fe type, being first used on the AT&SF. One member of the 3800 class, No. 3829, was the first 2-10-4, being fitted with a four-wheel trailing truck for extra support under the firebox. In this photo of unknown origin from the Gary Thompson collection we see No. 3900 representing the 3800 class. All were retired by 1956. Note the dual sand domes, useful in starting heavy trains on mountain grades — a feature also found on 2-8-2 No. 4002 following.