Do they have a large flat head similar to a washer? Or, are they the standard socket-head cap screws? The standards would have had a black oxide finish. The flat type could have been zinc chromated or cadmium plated. They would have been Allen sockets as Torx wasn't in use yet.
Many types are still available. Check McMaster-Carr:
http://www.mcmaster.com/
In the search box on the left, type in Socket Cap Screws.