I remeber riding these cars in a special excursion train when I was a kid and don’t remember much about them. I have never seen cars like these and they definitely look unique.
They sure look like RDCs to me-- spotting feature the mechanical bump on top for the prime movers. They may have been de-motored, and in that sense are no longer RDCs, but they sure look like RDCs to me. Any particular thing that made you think they were NOT RDCs? RDCs came in at least four different configurations, so these coiuld easily have been a config that doesn’t match common models…
I’d say they sure look like RDC-1’s converted to passenger cars (demotored, etc.). I may be wrong but I seem to remember reading somewhere that years back, some railroad bought some old RDC’s and converted them to passenger cars, maybe to use in commuter service??
A number of old RDCs of various configurations were demotored and rebuilt to coaches by Boise, and used as commuter cars on MBTA & VRE?, some ended up on Vermont Railway and about a year ago 6 of the VTR cars made their way into Ontario, where some of them are in service on a new private dinner train operation in the city of Guelph, ON.