In 1943 the Baldwin Locomotive Works constructed 25 4-8-4 or Northern type locomotives for the St. Louis-San Francisco Railway. Three of this 4500 class were oil burners assigned to passenger service, while the rest burned coal. Above we see the first of the coal burners, No. 4503, in a builder's photo I discovered in an antique shop. She and her sisters weighed 462,500 pounds and developed 69,800 pounds of tractive effort (raised to 71,200 with booster cut in). They had 74-inch disc drivers and 28x31-inch cylinders, and carried 255 p.s.i. of boiler pressure. Their evaporative heating surface totaled 4766 square feet, and their superheating surface 1508 square feet. Four examples of the Frisco's 4500 class survive, but No. 4503 is not among them.