Santiago - You note this as a "diesel wash rack". Quite true. But, in my younger days, I used to ride into downtown Chicago with my mother on the Burlington......always sat on the north side of the "double decker car" as that would provide a glimpse of the Baltimore & Ohio wash rack adjacent to the Robey Street roundhouse. AND a glimpse of a B&O Chicago Terminal 0-8-0 shoving B&O streamlined passenger cars through the wash rack! Steam lasted there until Spring 1958 (some say later - can't confirm). So steam would not be out of place switching your wash rack. Suspect one of Burlington's "unusual" 0-6-0's (rebuilt from 2-6-2's) pushed Zephyr cars through the Denver car wash, too.