No mopar had a black engine compartment (they were body color) unless the car was painted black. Most likely when the /6 was pulled to be rebuilt they redid the engine compartment.
I have a 72 Vailant and 73 Duster Both one built in July 72 and the other Aug 72. They each have black engine bay and have never been restored. Body color light tan. When I redo them I would rather paint them the body color.
Did Chrysler ever do black engine bays with a different body color? Just curious.