'53 Corvette chassis: what color?

I'm building a 1953 Corvette model made by AMT Ertl, and trying to decide what color to paint the underside of the chassis. You'd think they would give you the color, but they don't give colors for any of the parts. I'm assuming the underside of the chassis would be black like modern cars, but of course there's like a 40-50 year difference in design, so I'm not sure. Photos would be greatly appreciated, but any info will do.