A recent eBay find was this nice composite gondola lettered for the Yorkville & Western of Fred Schorr. I have two other models of this general type built by Pierre Bourassa.

I had simply thought of these as being composite gondolas, but there is more of a story. The prototypes were 52’ cars built during WWII to conserve steel plate. I found a good write up on the Valley Model Trains website: 

By the late 1930s, the 52-foot, 6-inch gondola had become the preferred design for the railroads serving Northeastern industrial plants….
During WWII, military needs for steel took priority. Rolled steel sheet, which was used for all types of light armor and ship construction, was particularly in short supply. Thus, American railroads received steel only after military demand was met. New cars were limited to those authorized by the War Production Board. With railroads handling the majority of all military and commercial shipments, there was a burden on the supply of rolling stock. Out of necessity, the railroads searched for ways to substitute other materials for steel. By reviving earlier composite car building practices, the AAR design teams replaced sheet steel with wood with steel systems added for strength.
Due to the length of the car, a fishbelly structure was necessary and the ribs provided protection from outward strain from the inside loads. In 1943, the builders replaced steel where wood would suffice. For structural integrity, in place of the already steel side, the designers created a truss of diagonal and vertical ribs. A wood floor was a savings and dreadnaught drop ends were applied. The War Emergency gondola dates from October of 1942 with the building program beginning late 1943 and continued into the middle of 1944.

The model seen here is an attractive model of this interesting prototype, but it is rather under sized really at only 42 feet long.

What Schorr and Bourassa did to make their models was take cast HO sides such as these and build up the rest of the car neatly. So while a plausible model, it is not really an OO scale model at all, at least not if compared to the prototype cars.

Of course, who is to say that in our world there were examples of similar cars produced that were shorter and lower? I’ll probably build up these loose sides someday into OO models, it would make a nice project and not overly complicated.

UPDATE: And, as noted in the first comment (I should have put this in the article to begin with), the sides on the car and in the second photo are almost certainly Ulrich sides. The instructions for this classic HO model may be found here in the HO Seeker site.