The C&O is Miloco or MinI scale, one came from the other. two halves and 17/64ths. The early cars were indeed Aluminum. The later cars were zinc alloy or pot metal in common terms. There are a few threads on these two firms in the two rail forum.
The other is either Alexander or Crestline Walthers but I think it is Alexander. Could potentially also be Scale Models as others mentioned. Good cars happy to take them off your hands lol.