The 1966 24 Hours of Le Mans was the 34th Grand Prix of Endurance, and took place on 18 and 19 June 1966. It was also the seventh round of the 1966 World Sportscar Championship season. This was the first overall win at Le Mans for the Ford GT40 as well as the first win for an American constructor in a major European race since Jimmy Murphy's triumph with Duesenberg at the 1921 French Grand Prix. It was also the debut Le Mans start for two significant drivers: Henri Pescarolo, who went on to set the record for the most starts at Le Mans; and Jacky Ickx, whose record of six Le Mans victories stood until beaten by Tom Kristensen in 2005. Regulations The year 1966 saw the advent of a completely new set of regulations from the CSI (Commission Sportive Internationale – the FIA's regulations body) – the FIA Appendix J, redefining the categories of motorsport in a numerical list. GT cars were now Group 3 and Prototypes were now Group 6, Sports Cars were still Group 4 and Special Touring Cars was a new category defined by Group 5. (Group 1 and 2 covered other Touring Cars, Group 7 led to the Can-Am series, with Group 8 and 9 for single-seaters). As Group 7 were ineligible for FIA championship events, the Automobile Club de l'Ouest (ACO) opened its entry list to Group 3, 4 and 6. The FIA mandated minimum annual production runs of 500 cars for Group 3 (up from 100 previously) and 50 for Group 4, which also had a maximum engine capacity of 5000cc. There were no engine limits on the GTs or Prototypes. As before, the Groups were split up in classes based on engine size, there was a sliding scale of a minimum weight based on the increasing engine size (from 450 to 1000 kg for 500 to 7000cc) as was fuel-tank capacity (60 to 160 litres). Along with the new Appendix J, after four years of focus on GT racing the FIA announced the International Manufacturer's Championship, for Group 6 Prototypes (2L / >2L), and the International Sports Car Championship for Group 4 (1.3L / 2L / 5L). Entries With the new regulations this year the ACO received a huge 103 entry requests. Such was the interest in Group 6 there were 43 prototypes on the starting grid and only 3 GT