A&Y Dave in MD
David Pfeiffer is retired. There is no one there right now that fills his shoes in terms of passion for railroads, although many of the archivists are friendly and helpful. David is still active--I hadn't seen him in the year prior to the pandemic shutting down access, but the archivists talked about him coming in to visit.
As to the original question: until the pandemic I was visiting the Archives regularly, about once a month for two years. I have yet to explore everything related to the A&Y, a Southern-owned shortline without revenue rolling stock. The annual reports (which were done prior to and after the Valuation) contain summaries of rolling stock and locomotives, but they are not detailed. There may be more yet to find when I start researching the Southern proper, but you would think that if detailed photos and other information on rolling stock were available, David P. or some other fan would have already pointed it out. You may find there are unique records for a given railroad, but I doubt that there is a generally useful "treasure trove" with respect to rolling stock photos and details in NARA II.
If someone like Mr. Kott would be able to provide the retrieval information for the books that contained the images he photocopied, I'd be willing to submit a request slip and use my digital scanner to obtain a more detailed set of images at my convenience. I aim to digitize virtually all of the A&Y records and I'm fortunate to live within 30 miles of College Park. So once the pandemic lifts, NARA is open to the public again, and I'm vaccinated, I'll be resuming my trips. I still work full time and I'm mostly interested in the A&Y and Southern, but I like to help others similarly fascinated--so long as it is still a hobby and not a second job.
David Bott, modeling the A&Y in '34