Original primer

I working on sanding to get rid of some surface rust on my 64 Dart. Does anyone know what color primer Mother Mopar used back when? I'm finding brown primer, which I remember was common aftermarket back then, but the paint looks original (what's left of it). Just curious.

After some serious investigation it looks like the primer on LA and Detroit built cars is some kind of NATO green. The body was dipped 22" from bottom and up. Also the wheels had that paint and they just shot black paint on the outer side.