In 1911 and 1912, the Atchison, Topeka and Santa Fe Railway modified ten 2-10-2 Baldwin-built locomotives into a new 2-10-10-2 configuration dubbed the 3000 class.

With a width of 12 feet (3,658 mm), they were delivered without their cabs and front low-pressure cylinders and were assembled after delivery.

The 48-inch (1,219 mm) low-pressure cylinders (on 90-inch or 2,286-millimetre centers) were the largest on any U.S. locomotive; these had to be inclined a few degrees to provide clearance.

[1] The boiler was also the widest of any locomotive; Railway Mechanical Engineer says "the outside diameter of the largest course is 112+7⁄8 inches (2,867 mm)."

They could also be operated in simple mode for starting; reduced-pressure steam could be sent straight from the boiler to the front cylinders at low speed, for maximum tractive effort.