Funaro & Camerlengo has released the PRR F28 depressed center flat car as a resin kit.
The PRR built two of these 52'6" cars, 435491 and 435492, with 2F-F1 six-wheel trucks in 1927. The cars lasted beyond the PRR in 1968.
The cars were conceived as an extremely heavy duty combination of the features of a standard depressed center car, with some of the advantages of a partial well flat.
Page 40 of Pennsylvania Railroad Flat Cars: Revenue and Work Equipment by the Pennsylvania Railroad Technical & Historical Society includes a photo of one of the cars with a Mesta machine Co. planer table load from Homestead, Pa.