In this view of C&NW 4-6-2 No. 1667 we note that the 1940s rebuilding of this group of Pacifics included, for at least some engines, the application of disc main drivers and a one-piece cast Delta trailing truck in addition to those features noted on the page for No. 1620 preceding. For the E and E-S classes the boiler pressure is given as either 185 or 200 p.s.i. and tractive effort as 36,692 or 39,667 pounds. Locomotive weight is specified as 266,000 or 276,000 pounds. The grate area is given as 53 square feet, with the evaporative heating surface being given as 3150 or 3124 square feet and the superheater surface as 691 or 746 square feet. (Sources are not clear which dimensions apply to specific locomotives in the later E or E-S groups.) No. 1667 of class E, shown here at Minneapolis in an undated photo by Robert Graham, was renumbered to 667 in 1951-52. Retirement for some members of the E and E-S classes began in 1937, but most engines operated into the late 1940s or early 1950s, the last being dropped from the roster in 1956.