At the moment I am traveling so don't have any documentation handy, but if I am not mistaken, the 40 Susquehanna box cars you are seeing were Mather cast offs from the Erie used in express service. The NYS&W had no interchange cars and only had the Mather box cars and some hoppers used in on line service. The 8 box cars you are talking about were purchased from the Lehigh Valley, but only had 6' doors and were not wanted by shippers, with all but 2 being sold off fairly quickly. Westerfield makes a nice model of the Mather box car, and I have 4 of them in express service on my '49 based Susquehanna layout.
