Interestingly enough, the Marketing East/Taurus Products/Trout Creek Engineering kit for the Rock Island reefer was also sold as a PFE R-30-13 - with notes from Nelson McCormick and Prototype Modeler.
I know, I have one of the PFE versions and have built it. It is certainly close the the PFE design if not exact. Since GATC was building PFE cars in the 1920s, it’s very possible that the Rock Island cars were copies. PFE routinely allowed use of their drawings that way.
