Thanks, Steve, I did respray all the main mounting brackets semi gloss epoxy black.
Steve's extension brackets appears to be black.
Brackets on the 10k car are definitely silver.
I didn't get around to doing any testing on mine, but I believe it is argent silver paint. The color is very similar to the rally wheels I have.
Steve's car is a Norwood build and mine is LA. Could be a plant variant, as we've seen with other anomalies...
I'll test with thinner later today.