The most definitive way to identify a car is to look at its papers. However, I am sure you will agree that this is by far the most difficult way to find the serial number.
The VIN-System, in use since the US Federal Motor Vehicle Theft Law Enforcement Act became effective in October 1984, is the proper way to identify cars. The VIN of modern cars is stamped into the frame. However, the Maranello factory has used VIN-plates on steering wheel columns since the early 1970’s.
On cars produced before that date, the only chance of identification is the serial number tag, normally placed somewhere in the engine bay. Early production cars do not have this, but do have the serial number stamped into the frame.
To protect cars from theft, European cars from the mid 1970’s to late 2002 production had the serial number etched into every window. Some modern cars later than 2002 production, and mainly from France and Southern Europe, still show these etchings today. This feature seems not to have been used outside the European market.
Since the 612 Scaglietti was launched, the cars, except those in the F430 series, show their serial number on the lower part of the front window on the driver’s side.