Key Switched alarm system-anyone else seen this?

[pritch]

My Panel has this key switch on the fender. At one time, it was hooked up to some kind of alarm. There are switches-like dome light switches-on every door and the hood. All the wires that are still hooked to these switches come to a point on the firewall just inside where the key switch is. Whatever was there that the wires hooked to is long gone. I always figured that it was some kind of aftermarket deal that a PO had put on, and I still believe that, but at our local car show Saturday there was a '67(?) Vette that had a similar switch. The guy said that it was factory, and his ignition key worked it. (Mine is keyed diferent) but it started me wondering if there was a factory alarm system availible.