They are ok for excursions but you gotta be careful. During my most recent visit to Steamtown I rode behind Lackawanna 664 and 663 from Scranton to Tobyhanna and back. Both F units. Cosmetically they were phenomenal. Mechanically? Well…
Both were smoking real bad and seemed to be burning oil judging by the smell and smoke color. Once at Tobyhanna, the engines stopped responding to throttle commands which left the crew baffled. They had to diagnose the issue which held up the departure about one hour. I later learned that 664s governor had stopped working, and it had to be fixed on site. Good thing too, as we were one and a half hours travel time away from the nearest engine that could’ve rescued us.
I didn’t let it bother me that much as the staff were friendly and we had a shaded train station to sit underneath while we waited. Others weren’t as patient.
SMS has a lot of experience fixing engines like this with a large amount of electromechanical parts and old school computers that had no circuit boards.
When you get a chance, take a look at the operation manual for one of these engines online. Crazy to see how many relays, resistors, and contactors are used to accomplish what would be controlled by microchips and screens nowadays.
And yes, I too wouldn’t mind seeing them pull some freight. Although I don’t see them doing well pulling long trains of todays freight cars, which have gotten a LOT heavier since the 1950s.