Does anyone know off hand of a source for caboose voltage regulators, especially those used by International Car?

What voltage are you trying to regulate? It might be easier to but off the shelf or build one yourself.

To be honest, I don't know, but I believe 12 volts. There is a Spicer drive generator, a power receptacle and a 4 cell deep cycle battery in the system.

The regulator on the car was destroyed by vandals prior to our acquisition of the car. A source has given me a manufacturer name of Safety Electric, but they don't appear to be in business anymore based on a search I made. We haven't spun the generator yet to see what kind of output voltage it has.

If it is 12v go down to Napa Auto Parts as that is basically an automotive power system.