My dust caps appear to be coated with a brown/green looking substance. While looking at some wheels at MSA that had the hubcaps removed, I noted most of the dust caps to be zinc chromate colored.

Did Nissan change during the 1971 year, or are mine an aftermarket verison of the factory part?

Randy, the dust caps on my red car (7/71) are also the dark finish you describe. I think they are original, so there has probably been a change in finish at the factory.

Thanks Arne. I was hoping your red car had the same thing as that would give credence to the originality of my dust caps.

A fellow at the West Coast Nationals had a nice clean 12/71 car with a 5XXXX serial number with the zinc caps, and he said his were original.

My 6/70 are the dark color as well.

Dark here as well. Looks like a black or olive chromate treatment to me.