The Grand Trunk Western's U-1-c Mountains, Nos. 6037-6041, had 26x30-inch cylinders, a driver diameter of 73 inches, and a boiler pressure of 210 pounds per square inch. Boasting a locomotive weight of 354,110 pounds, they developed 49,590 pounds of tractive force. With a grate area of 67 square feet, these engines had 4049 square feet of evaporative heating surface and a superheater surface of 1087 square feet.

The GTW gradually equipped the U-1-c class 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 the Steam Locomotive Archive. These handsome 4-8-2s spent their later years on the Detroit-Muskegon line and ended their careers in suburban service between Detroit and Pontiac, Michigan. 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.