Found two more MONON-related photos I've never seen before, attached.
They are from one of nineteen "Trains Albums of Photographs", the 18th one, entitled "Railroads of Chicago", published I think for sale at the fabulous 1948-1949 Chicago Railroad Fair. The first photo is a shot of a short train just out of Dearborn, labeled "The Hoosier", though without one of the ex-USA RPO conversion in tow, I don't think so. The second one is of ATSF's Grand Canyon ready for departure from Dearborn. Note the ex-USA RPO to the far right.