The Nason gondola was introduced in their sixth edition (1940) catalog, where the only text is that the kit is under construction, i.e., not yet released but coming soon. The photo in that catalog, reproduced below, shows that it looks like a nice car but no other construction details are noted. Note also the outside third rail in the photo.

An article in the January, 1989 issue of The OO Road (on the Stephans’ Railroad Directory) pointed me to a review of this car kit in the October, 1940 issue of Model Railroader. At that time the Trade Topics column was a review column and they note in this issue that

With this issue The Model Railroader has lost another advertiser because the publishers refused to alter or apologize for a Trade Topics writeup which did not suit the advertiser. We mention this to emphasize the editorial independence of this column of comment on model parts and kits.

With that, the first review up in this issue is of our elusive Nason gondola. Of it they note:

Here is a OO Gauge Pennsy gondola kit that is very complete. The wood framework is of good quality and cut to size, and the cardboard sides are painted and lettered. Embossed rivets are incorporated. Cast bronze truck side frames are used along with an aluminum underbody casting.

That is pretty much all there is to the review but it is enough to show 1. the car was produced and 2. what the car would look like if you have one.

But if that were not enough it was also reviewed briefly in the October 1940 issues of Miniature Railroading and The Model Craftsman! In Miniature Railroading we learn,

The Nason Railways, Inc., of Mt. Vernon, N.Y., have added a new Pennsylvania Gondola to their line. The car presents a realistic, attractive and sturdy appearance…. One of the kit’s many features is the effective method of fastening the brass side ribs. Steel escutcheon pins are used through punched holes at the top and bottom of the ribs, making for extreme simplicity and durability. 

And in The Model Craftsman we see that same exact text and also the note that “This model, the manufacturer advises, is easy to build, yet difficult enough to require skill in construction.”

This car was also produced in a version for the B&O in 1941. These are only rarely seen listed for sale, and being introduced so late in Nason production it must be rather rare.