Another possibility is these are the surplus cars that the RGS is disposing of in a negotiated settlement with the General Machinery and Supply Co. whereby the RGS retained 46 of the original 125 Miller cars. Then this might be 1942 whereby this view is of some of 78 cars that are outbound from the RGS. See pages 386/387 of RGS Story Vol. XII for more information.
The real clincher would be to get a clear scan of the first car to see whose reporting mark and car number that appears to be near the top grab iron rung.