My link is this: "Classic Ferraris - the legend on the road" by Brian Laban (a book, so can't prove myself!)... however you are right about the swb being the first production car the discs were officially implemented (though it's not strictly a racecar... like most Ferraris in the old days)...
My question... how many chassis of the Ferrari F50 GT were built? (don't rush with the answer pay attention to my wording!)