I just received the Eastern Seaboard Models Magor/PC&F XIH box cars. For those unfamiliar with the company, this is their first HO scale offering, after years of excellent N-scale products.
Bryan has been posting updates, photos, and videos on a regular basis which highlighted testing and various rejections (including just as they were about to ship) to ensure these models were up to their standards.
I haven't done any significant research on the prototype since the NH version was built mid-1953 and just sneaks into my modeling era. But these are actually two closely related prototypes, 300 cars built for BAR by Magor in 1950, and another 150 cars (plus 100 for the NH) built by PC&F.