Recently I went to the Simeone Auto Museum in Philadelphia Pennsylvania for a preservation seminar on their Shelby Cobra "Daytona" Coupe. This car has never been restored and had what was called a "preservation" by a well known restorer. This car also has the black pulley and blue fan detail on its alternator. Fred Simeone said during the presentation that this was indicative of the early hipo alternators according to the restorer and I was looking for confirmation of this. The later hipo alternator I have which I believe to be an original has the cad plated pulley and fan.
I went to the Simeon Museum today and after they drove the Daytona and other cars around the parking lot, they let you check them out close up. I've seen this car with the hood up a few times but never noticed the alternator pulley and fan are both blue.
I was thinking maybe when this post was made in 2016 the pulley was black and they swapped it for some strange reason but I checked pictures I have from 2014 and it was blue then also.