Two representatives of the Southern Pacific's famous GS-series 4-8-4s are extant. The best known is "Daylight" No. 4449 of class GS-4, which pulled the American Freedom Train in 1975-76 and is operational. The other survivor is No. 4460 of class GS-6, preserved at the Museum of Transportation in suburban St. Louis, Missouri, where I photographed her on July 12, 1990.

The ten members of the GS-6 class were "war babies," erected by Lima Locomotive Works in 1943. Although they had the skyline casing and contoured smokebox front of the earlier "Daylight" groups, due to wartime steel shortages they lacked their colorful skirting. With the arrival of the 1943 engines the designation GS, which originally meant "Golden State" after California, was changed to "General Service" to satisfy War Production Board restrictions on the erection of new passenger locomotives. No. 4460 and her sisters weighed 468,400 pounds and, thanks in part to a reduction in driver diameter to 73½ inches, developed 64,600 pounds of tractive force — comparable to that of the GS-4s — despite their lowered boiler pressure of 260 pounds. Their pulling power when starting was augmented by a booster, and like other SP 4-8-4s they were oil-fired. They had 27x30-inch cylinders, a grate area of 90 square feet, 4855 square feet of evaporative heating surface and 1835 square feet of superheater surface.