The first prototype was built by the Ferrari factory in early 1982. This "mule" had no interior and was only meant to test the mechanical components. This car was followed by at least 30 other prototypes, all built by a Turin based firm called ITCA, which would also build the chassis and bodies for the normal production Testarossas.
Of the 30 prototypes, 12 were complete cars (in Euro LHD, UK RHD and USA versions), while the rest were incomplete cars to test all the individual components. All prototypes were later used for crash testing for Type Approval and were later destroyed. Only three cars survived this horrible death and were later used by Ferrari’s Experimental Department for further testing.
It is yet unknown if the prototypes also had serialnumbers. If so, then they would probably be in the 47xxx range. It might also be possible that the cars had no normal serialnumbers, but just a three-digit internal number.
The pre-production of the Testarossa started in January 1984 and normal production started in July. The earliest known Testarossa is s/n 53081, last known to be in The Netherlands. The two Testarossas shown at the Paris Salon were s/n 53283 and s/n 53285. All these (European) pre-production cars can be recognized by the special side blinkers. It might be possible that s/n 54051 is the first "real" production car and that this car has normal blinkers.
Special blinkers on pre-production European cars (this is from s/n 53081)
s/n 53283 shown at the Lido Club in Paris [Source: Ferrari.com]
s/n 53285 shown at the 1984 Paris show, at the Pininfarina stand [Source: Ferrari.com]