Every once in a while you learn something new about what you are modeling in the most unusual circumstances. For me, it occurred recently during an operating session at another person's layout. The host and my engineer (I was the conductor) were talking about the efficiency of the switching moves we were performing... or perhaps the lack of efficiency on my end... and he mentioned that when he was working at Southworth Machinery (see here) he would see the train go back and forth without any sort of reasoning.
As it turns out, he was an accountant in a financial firm that would audit the Southworth books on occasion. He was given a temporary office in the upper corner facing the tracks and could watch the D&H switch the three sidings while running the numbers. More interestingly, he commented that when he was there (the late 1960s and 1970s) Southworth would receive huge Caterpillar tractors on flat cars that were so wide that the wheels had to be removed and shipped on separate cars. He didn't recall ever seeing them ship out stuff via rail.
Of course, by the 1980s things might have changed. The picture I have shows a boxcar spotted on the track, perhaps with large machinery parts inside.
Regardless, it is an interesting detail to model. I was planning on just putting some generic tractors on a flat car for service to this place but now I will look into something more realistic.