Gerry,
The original one I have, (complete with tiny Bosch logo embossed on it) appears to be yellow Cadmium. That would have been a typical original finish. Cadmium was traditional to use for most steel parts (such as FI lines, nuts and bolts) but isn't used much any more. I would not be surprised if over the course of production, the Cadmium finish was both yellow and silver.
A replacement bracket I have is probably zinc plated, and silver in color.
You can, if you are refinishing things, get both zinc and cadmium plating, both in silver and yellow. The underlying plate in both is silver in color and the yellow color comes from a phosphate wash afer the plating which provides additional protection.