There were at least two earlier cars - 56275 and 56277 were at the Geneva show in 1985 when the 412 was launched (one was on the Pininfarina stand).
Seller will probably be disappointed!! (Even if I don't really understand why it should be a real "plus", but as you would say: IMHO) Always impressed by the knowledge some of you have got. Please, just curious, how can you "guess" its #???
In my case, through years of work compiling a database, noting adverts and collecting photos of every 412..
The same car is now advertised as 06/1998 for euro 75k ---> Ferrari 412 as SportsCar/Coupé in Tiefenbronn.