The design of the Type 904, marketed as the Carrera GTS, was quite a step for Porsche’s sports racing cars. The gradual metamorphosis from 356 to 550 to 718 jumped to the 904 which benefitted from the knowledge gained with Porsche’s foray into Grand Prix racing with the Type 804. Utilising an all new steel box frame chassis to which a glass fibre body was bonded, the suspension was now by “A“arms and coils front and rear. It was designed to use the new 6 cylinder Type 901 engine but this was not race ready when construction got underway so the Fuhrmann Type 587 4 cam from the previous sports cars was installed initially. To keep to the GT racing regulations of the time a minimum of 100 cars needed to be built before homologation could be granted and to meet this figure Porsche subcontracted the manufacture and fitting of the glass fibre body to aircraft manufacturer Heinkel. This design and construction method also kept the costs down and made repairs easier and cheaper which was necessary as Porsche would need to sell the majority of the 100 odd 904s to private customers. There were also the not inconsiderable benefits of lighter weight and better aerodynamics. The 904 first appeared on the International scene running as a prototype at the Sebring 12 Hours in March1964, where the Briggs Cunningham car, driven by Briggs himself and Lake Underwood won the up to 3 litre prototype class. In April, with the 904 now homologated as a GT, Colin Davis and Antonio Pucci led a factory Porsche 904 one-two in the gruelling 720Km Targa Florio road race in Sicily.