underbody color 1966 coronet?

Hello, working on my 66 coronet project and currently detailing the underside of the car. its hard to tell what color was originally painted under there if any. The car was originally a pale yellow, but I see no signs of that anywhere. Were they painted the same color as the rest of the shell, left bare, or painted black. Obviously some areas are undercoated, but the other areas, such as the trans tunnel, behind the back seat, and the underside of the trunk floor is where I was wondering about. Any info would be appreciated. I've spent so much time and money on this car, I don't want to go cheap here. Thank you in advance.

I bet the underside was originally primer, with overspray from when the sides were painted. Most mopars were like that.
I over restored my cars and painted the bottom the same as the top.

Here are some nice pics of a restored '71 RR, I can't say for sure if yours would be the same, but i would assume it would be.
http://www.pedaltothemetal.nl/index...971-plymouth-roadrunner-match-sold?Itemid=124

should have been a flat black on the floor pans with a little body color over spray along the perimeter of the floor pans.