The link posted by Rusty Traque says the cars were produced by Intermountain, lower right corner. Athearn made them in HO; Atlas, Lionel, and MTH have made them in O ga.
The early Center Flow covered hopper cars were cylindrical, generally 3200 and 3500 cubic feet capacity, with either 70 ton or 100 ton trucks depending on a commodity's weight per cubic foot. Starting in 1965 the shape changed to a more rectangular design based on the angle of repose of dry commodities and how those commodities filled a car's compartments. 2970, and later, 2980 cubic foot cap'y cars were introduced for dense commodities like cement, and ultimately becoming as large as 5800 cu.ft. All Center Flow cars had bulkheads inside, they were part of the car's structure. The number of outlets indicates the number of compartments. ACF never described the cars as having "bays", always as 2, 3, or 4 compartment cars. Cars were equipped with 20" or 30" dia. hatches, or elongated or continuous hatches (usually for grain service). Outlets were gravity, gravity-pneumatic, pneumatic (plastic pellet service), & butterfly. ACF also made and leased pressure differential Center Flow cars.
I was employed in sales by the Shippers Car Line Div. of ACF from 1965 to 1997.
