Carroll Shelby was brought in to boost Ford's struggling GT racing program in late 1964. Shelby, who won Le Mans as a driver in 1959, turned things around. His team reworked the GT40 and, with Ford engineers, replaced its 289-cubic inch engine with a big 427. As we know from the movie Ford Vs. Ferrari, in 1965, The Ford GT40 actually "won" the 24hr Race.
Each is numbered on base 1 of 1965, 2 of 1965 and so on