D&RGW ?4

Denver & Rio Grande Western (now Union Pacific) snow plow / flanger in UP North Yard, Denver, Colorado.

Can anyone help me identify the number of this car? I was unable to get more than the trailing 4.

Hasselblad 500 EL/M, Carl Zeiss CF T* Sonnar 4/150, Fuji Velvia 50 120 slide film