90 originally pulled sugar beet trains for the Great Western Railway of Colorado, and it was the largest of the company’s roster.

90 was purchased by the Strasburg Rail Road, who were looking for a new engine to pull the ever-increasing train loads, which was becoming too much for No.

[9][7] Based on the Russian Decapod design, the locomotive was engineered to deliver high power on lightweight tracks with minimal axle loading.

90 was the largest and most powerful road locomotive on GW, primarily used for hauling sugar beet trains of 40–50 cars to the Loveland, Colorado, mill.

[5][3] During World War II, it was modified with an extended smokebox to accommodate poor-quality lignite coal.

90 served mainly during the autumn harvest season and later operated occasional excursion and campaign trains.

90 hauled the Intermountain Limited excursion as part of the National Railway Historical Society (NRHS) Convention, working alongside Chicago, Burlington and Quincy 5632.

[3][2] Competing bids aimed to keep it in Colorado for further excursion use, but GW opted for SRC's cash offer.

[6] That same month, Ross Rowland's High Iron Company sponsored two mainline excursion trains, and Canadian Pacific (CPR) 4-6-2 locomotives Nos.

90 was returned to SRC to pull its first official tourist trains there, and it was celebrated as the railroad’s main attraction.

90 was temporarily backdated to its late 1960s appearance with the original SRC "egg" logo, whitewall wheels, and gold pinstripings for the Steam Strikes Back photo charter, commemorating SRC's 60th anniversary.