The Milwaukee Road's first large order for 4-8-4s went to Baldwin Locomotive Works in 1937 for 40 class S2 Northern types. These locomotives featured a General Steel Castings one-piece cast steel bed, and sported Boxpok drivers of generous 74-inch diameter although they operated principally in freight service. All locomotive axles had roller bearings. Their cylinder dimensions were 26x32 inches, and they mustered a boiler pressure of 285 p.s.i. With these specifications they produced 70,816 pounds of tractive effort and weighed 490,450 pounds. Other dimensions are given in the comments for No. 210 following. No. 206 represents the S2 class in this Baldwin builder's photo; it was dropped from the roster in 1956.