According to Atlas:
"The three-compartment ACF® 3560 Center Flow Covered Hopper was designed for the transport of high-density dry bulk ladings of 50 – 60 pounds per cubic foot. About 2,214 cars were built from 1967 – 1972. This Center Flow Covered Hopper transported a wide variety of commodities, including salt, fertilizer, starch, bauxite, and clay."
Ray Breyer
Modeling the NKP's Peoria Division, circa 1943