Keep in mind that the acronym "NOS" has no correlation to the component being an original part. I've seen red "NOS" NAPA Heater Hose from the early seventies. It was NOS Hose but not original to any particular name brand manufacturer.
New Old Stock is also a relative term. How "old" does a part have to be before it is considered NOS? Another aspect worth mentioning is that Chrysler did not manufacture most of their components. They commissioned Independent Parts Manufacturers, under licensed engineering specifications, to manufacture their components. Arvin for instance was one of the approved suppliers for Chrysler Exhaust Systems. My Company currently manufactures 1969-1974 E Body Exhaust Systems under Chrysler's licensing approval and in compliance with the same engineering specifications that were used back in the late sixties and early seventies. How long until our Chrysler approved/commissioned Exhaust components are classified as NOS?