Just because YOU have never seen it…
And yes they were the exception, not the rule…
Shown on page 201, fig 186, of the the 1940 Car Builders’ Cyclopedia, WESTERN MARYLAND 50-ton, 50 foot (not 51’ or 53’ or whatever) all welded flat car with Duryea cushion underframe. Build by Greenville Steel Car Company - equipped with a side mounted brake wheel stand.
If I can successfully scan it, I will post a picture for all you non believers as I have not found a picture on that “wonderfull” thing call the internet.
Athearn did mistakenly, or purposely not extend the decking out to the sides of the stake pockets - BUT - on this same page of the Cyclopedia, there are are four other flat cars - not one of the other four flat cars have there decking extended past the sides - so that might not have been as “universal” at that time as you think.
It is clear to me that the Athearn car is a composite of the cars shown in the 1940 Cyoclopedia. Interestingly, also shown a few pages later is a 200 ton four truck flat car just like Athearns “heavy duty” flat car.
And, most of the pictures of the 50 flat cars reflect many of the roadnames Athearn offered their cars in - NKP, C&O, WM, PRR, UP, etc.
There are also 50’ gondola’s about 17 pages later that look just like the Athearn cars.
I will check later for the other car types in the Blue Box line - anyone else out there have a the 1940 Cyclopedia? 1352 pages of prototype FACTS for someone who models the 40’s or 50’s - like me - not just speculation.
Pick on the Blue Box cars are you want, but a study of pictures from the 40’s and 50’s show most all of them to be very “representative” and reflect the proportions and flavor of that era even if they are not rivet perfect.
But what do I know, I just have a library of “actual” books and magazines.
Sheldon.