Angela- Athearn is doing a 65' mill gondola which will be a good stand-in or starting point for the mill gon (I don't believe any "USRA" mill gons were built; there may have been a proposed design but AFAIK only the box cars and 40' gons were built).
There were thousands of USRA mill gons and clones built from 1919 through the 1920s. The Pennsy, B&O, NYC/PMcK&Y and Reading bought true USRA mill gons. The "clone" of the design was the "standard" mill gon in the 1920s for the NYC System, B&O and Reading.
