The Mk 1, the oldest of the cars, won in 1968 and 1969, the second chassis to win Le Mans more than once. (This Ford/Shelby chassis #P-1075 was believed to have been the first until the Ferrari 275P chassis 0816 was revealed to have won the 1964 race after winning the 1963 race in 250P configuration and with a 0814 chassis plate). Using an American Ford V8 engine, originally of 4.7-liter displacement capacity (289 cubic inches), it was later enlarged to the 4.9-liter engine (302 cubic inches), with custom alloy Gurney–Weslake cylinder heads.