A&Y Dave in MD
I now have a concrete example of what the ICC documentation for rolling stock would look like. Tony Thompson mentioned the "53" section, and I dug around in my backlog of documents. Here is what Section 53 looked like for the Southern Railway (attached PDF). It is more detailed than I suggested, but less detailed than photographs and drawings as you might find in railroad-specific diagram books.
Hope this answers more definitively what you are interested in.
David Bott, modeling the A&Y in '34