These models date back to the early days of N scale (late 60s / early 70s). They were originally imported as part of the Aurora/Minitrix "Postage Stamp" line. After that they were imported by Model Power (up until about 1980). More recently, they were imported by Walthers (in Roco packaging) -
I'm not sure what specific prototype these models might be based on (if any), but going by the number of side panels (six) and the trusses next to the doors (which slope away from the doors rather than towards them), the prototype is likely an ACF-designed "Howe Truss" box car.