The primer bath color can be found behind your door panels and about half way up the firewall on the interior side.

My car (70 Dart) had a medium charcoal grey color dip line, and not the lighter gray that I see in car magazines and internet photos. Maybe it's the camera flash that makes the grey look lighter I don't know. Maybe each plant had a slightly different mixture of whatever they used and it changed as they replenished it over time?