The Rio Grande's second order for 4-8-4s, which it styled "Westerns," were the five locomotives of the M-68 class delivered by Baldwin Locomotive Works in 1938. They weighed 479,360 pounds and produced 67,299 pounds of tractive effort. With 73-inch drivers and 285 p.s.i. of boiler pressure, they had cylinder dimensions of 26x30 inches. Grate area totaled 106 square feet, with an evaporative heating surface of 5506 square feet and 2336 square feet of superheating surface. These high-horsepower engines, used in passenger service, had roller bearings on all axles plus a combustion chamber of 139 square feet and thermic siphons totaling 122 square feet. Their design was the basis for the Missouri Pacific's N-73 4-8-4s of 1943. No. 1804, final member of the group, posed for the Baldwin builder's photo; it was sent to the torch in 1954.