The cars features in that article were all full 1/4" to he foot scale. The only exception was the All Nation Jersey Central express box car. The reason for that error originally made by General Models in the 1940s is described as well. While an error, their cars are still acceptable in the O scale community.
The Walthers, Westbrook, Train Craft and other period kit built cars were very close to prototype scale in size, although rather generic in detailing. It all depends on how much additional detailing or changes one is willing to add or make with any of these kits or to previously built cars found at train meets.
While most older Lionel products up to the 1980s were more or less under-sized, Lionel did and still does produce a number of full scale cars. (Actually, Lionel produced some full-scale freight cars in the late 1930s along with a full scale sized N Y Central Hudson locomotive. All are now rare, high cost collector's items). Some of these newer scale Lionel cars include a PRR H-30 style covered hopper, a steel PFE reefer, a wood bodied express reefer milk car, a Pullman designed PS-5 flat car and a few others as well.
The Atlas Industrial Rail products originated from the toy train field. But its best to check them with a scale ruler and some idea of what the prototype dimensions should be. Never know what might work!
With Bachmann, some of their items are re-issues of previously made models. Their new "Peter Witt" streetcar is full scale but has a modernized front end used by only a few traction companies. As for the On-30 narrow gauge equipment, some is scale and some may be fanciful. You need good eye and know what you want and like. It differs to a degree from the more usual On-3 1/4" to the foot scale in some but not all respects.
So far as I know there is no table of cross reference. The O scale field is very scattered with producers that made things for a while, then they disappear (producers or the items). Others take over and change previously made products (Atlas comes to mind, in its Trainman line of freight cars once done by Atlas/Roco in the 1970s. Also the former Intermountain and Red Caboose cars Atlas now makes). And let us not forget Weaver, which got its start making wood and metal craftsman type kits for freight cars, most of them being prototype-specific. Their ready to run cars are also full scale. But to make such a list would be only t o provide a brief 'snap shot' as to what is or could be available at that point in time.
Just how much are you interested in building freight cars from kits?
Names to look for include Scale Craft, Train Craft, Rail Craft, Lobaugh, Walthers, General Models, Athearn, All
Nation, Zimmer, Thomas, Westbrook, Bob Peare, North Jersey Car Co., Main Line Models, Weaver Quality Craft, Henry T, Sun Coast, Chooch (older and newer), Berkshire Valley, Atlas (1970s).
Then, Menzies/Pacific HO (they took over making the Athearn O scale kits, Locomotive Workshop (ditto), Old Pullman (ditto again) and Box Car Jim (last ditto on the former Athearn line), Intermountain, Red Caboose and Mullet River.
These are names dating from the late 1930s up to the current day. Most have come and gone over those decades. Yet examples of their product are still available FOB (Fresh Out of Box) as originally made. They await a pair of willing hands with a few tools to bring them to life. So too with previously kit built cars looking for a heavy dose of TLC to bring them closer to their potential as good or to become even better models.
For ready to run stuff out there be it new or used, a good eye and a scale rule will help identify pieces that are closest to scale and accuracy.
Explore the possibilities!