James,
The "sport model" name was indeed used by D&RGW crews. I was fortunate to have know a number of them including Frank Wright (D&RG 1915-1980), Clarence Russell, Tony Matkovich, and others. Frank Wright ran 479 at 45mph on the Shavano between Gunnison and Sargents. T-12s could run fast in their early days, but not later.