What colour should I paint my 1972 step bumper?

[1968_K20_4x4]

Hey everyone.

I have a 1972 K20. The rear step bumper has been painted black and I'm wanting to put it back to original. The truck has a painted white front bumper which I am keeping. I assumed that the rear step bumper would have originally been painted white to match the front. However it looks like under the black paint there is silver. So my question is, was the step bumper on these trucks originally painted silver? Even if they came from factory with a white front bumper?

Most trucks I have seen have a silver step bumper. However most guys are also running chrome front bumpers. I want to know what it should be if you have the steel white front bumper.

Thanks!