I'm not sure which specific prototype these models might be based on, but they look a lot like the SP/SSW B-70-36. These 40'-6" hi-cube box cars were all built to the same basic design by Pacific Car & Foundry in 1966 and featured 5001 ft3 capacity, Hydra-Cushion underframes and 10'-6" Youngstown sliding doors. These cars came to be nicknamed the "Ugly Ducklings" due their awkward apearance. They were intended for appliance service.
This model is also used to house Micro-Trains' motorized track cleaning car -
