Am I the origin of the rumor you quote about the 6C3000 CM Spider?
If so, I might have been misunderstood. I don't think it's anything close to a replica. I've been said from 'inside people' at the museum that today's car is not/would not be the Merano 1953 winning car and, after some doubts, I would indeed believe it's not that actual car, since close look at the details would confirm there are differences.
The use of that 6C3000 CM as testbed for odd disk brakes (you know, with a pump to cool the liquid in order to prevent it from boiling !
) is quite well known, and would indeed prove that the car in the museum is indeed an old racer/test car. The doubt is only on Fangio's winning 6C identity, possibly confused with a similar car crashed by Sanesi during a test session in Monza. So were there one or two 6C3000CM spider? Does some of the old men at Arese confuse a second Colli Spider with the following 6C3000 PR
, known for having been crashed at Monza before having been immortaled on pictures?
About a "black list": there's no mistery around the replicas at Arese. I think they are publicly declare as such. A look to the museum catalogue book should even show it indicated for each one. Now, as I wrote above, there are also cars rebuilt from authentic spares, but fitted to different models or adapted, or with mock/improper engines, etc. A comprehensive list of all shortcomings of the museum disply would be, er, unfair, IMHO, if you consider the real issues about the museum's location (building in need of conservative works, for instance), maintenance and restoration of the cars, public access, etc.