When was the cylindrical covered hopper introduced? I'm modeling in the 1950-70 era and have seen a couple hoppers that I must have provided they fit the era. I believe these are in my ballpark but I want information from more learned modelers/railfans. Thanks.
If these are the style by Bowser in N and Atlas in HO then I think they were ACF cars, and were like a precursor to the centerflow's. The cylindrical's seem to have early 60's build dates from the Atlas ones i've looked at closely. HTH
