With Monterey RM auctions coming i have some issue with Maserati 3500 GT Spyder Prototype’s description.
https://www.rmauctions.com/lots/lot.cfm?lot_id=1067923
RM states that:
“One of a believed three Vignale-bodied prototypes”

But of all Convertible prototypes and one-offs, there were 5 Vignale creations, including one Special and 4 prototypes:

I have contacted Maserati Classiche and awaiting reply

3500 GT Convertible prototypes:
Prototypes:
AM101.010 Touring ’58
AM101.124 Touring ’58
AM101.126 Touring ’58
AM101.268 Frua ’59
AM101.504 Vignale ’59
AM101.504/C Vignale Speciale ’59
AM101.505 Vignale ’59
AM101.623 Vignale ’59
AM101.678 Vignale ’59

 

Update:
Maserati Heritage was unable to answer my questions because they are still researching their history.