The Grand Trunk Western owned five 4-8-2s in class U-1-c, delivered by Baldwin Locomotive Works in 1925. They incorporated some typical modern Canadian National Railways steam locomotive features, including the Elesco feedwater heater, all-weather vestibule cab and Vanderbilt tender. Originally assigned to heavy passenger service on the Chicago-Port Huron main line, these Mountains were displaced by the more powerful 4-8-4s of class U-4-b in 1938 and U-3-b in 1942 — and perhaps for a time by the earlier class U-3-a of 1927, until those engines were withdrawn from passenger service in the 1930s. The U-1-c Mountains, Nos. 6037-6041, spent their later years on the Detroit-Muskegon line, and ended their careers in suburban service between Detroit and Pontiac, Michigan.

This group had 26x30-inch cylinders, a driver diameter of 73 inches, and a boiler pressure of 210 pounds per square inch. With a locomotive weight of 354,110 pounds, they developed 49,590 pounds of tractive force. The GTW gradually equipped these locomotives with disc drivers. As shown here in this view by James Adams from Rail Photo Service, No. 6037 still has the outer drivers spoked, but by the end of her service life she sported a full set of Boxpok drivers, as seen in a photo on the Grand Trunk Western page of Richard Leonard's Steam Locomotive Archive. Sister engine 6039, the only survivor of this class, is at Steamtown National Historic Site in Scranton, Pennsylvania, with the possibility of being restored to operation.