This model dates back to the early days of N scale (late 1960s). Atlas offered a similar 40' steel box car around the same time - manufactured in Italy by Rivarossi. The Roco-made car is the "tall" one (around 10' high), whereas the Rivarossi model was a bit shorter (around 9' high). Also, the doors are a bit different. I'm not sure when this model was discontinued, but it certainly didn't live long enough to make it into Atlas's "Trainman" line.
I don't know which specific prototype this car might be based on (if any), but it looks a bit like a PS-1. One of the most successful freight car designs of all time, over 76,000 PS-1s were built by Pullman-Standard between 1947 and 1968.