FYI, the A class locomotives were the four streamlined Atlantics (road numbers 1-4) built for Milwaukee Road's Hiawatha and were the first built with streamlining and for cruising at 100 mph speeds. #3 was retired in 1949 and cannibalized to keep the other three running; the rest were retired in 1951 and were scrapped the following year (according to the information I've seen).

Did the locomotive in question still have its shroud in place? Could you make out the wheel arrangement? Don Ross has a photo showing two of these locos being hauled to Chicago for scrapping in 1952; it's possible the locomotive you mention could be the other one of the three that were retired the year before (and may not have been hauled to Chicago), or it might even be #3. It certainly would be nice to see the actual photograph.

To that end, I'd suggest contacting the Milwaukee Road Historical Association to see if you could get permission to scan and post the photo online or perhaps get in contact with the photographer and ask him/her to post the original online.