Original engine colors??????

Man this has been beat to death. My brother bought a 1970 Duster brand new. He ordered it 69 so it was an early built car. His engine was red. On top of that every color guide I have seen have been wrong. Yes even Chrysler's. They did it so they didn't have to stock so many different colors of paint. The only way to know for sure is IF you know the car has never been redone. How many of those are left?