This model dates back to the early days of N scale (late 60's / early 70's). It was originally imported as part of the Aurora "Postage Stamp" line, and later on by Minitrix / Model Power.
Although clearly a hopper, this model was marketed as a tank car (an unusually glaring gaffe, even for early N scale). As for what prototype it might be based on, I guess it's at least close to this 59' / 3960 CF centerflow hopper (built for the NYC by ACF in 1961) -
