Four cars were entered: two for Shelby American, and one each for Briggs Cunningham and Ed Hugus. In the end though only two arrived alongside a works-entry Cobra Coupé from AC Cars. The Sunbeam Tiger was to be the Rootes Group answer to the AC Cobra. It used the 260cu in (4.3L) Windsor engine from Shelby American. The body was developed from the Alpine with Lister Cars, but being made of steel it was far too heavy. The 275 bhp could only get the car up to 230 kp/h (145 mph). Aston Martin shut down their racing department when John Wyer left to manage the Ford program, selling off the three DP prototypes. Mike Salmon bought one of the DP214s and entered it as a privateer. Similarly, the Jaguar E-Type Lightweights were becoming obsolete and only two privateer entries arrived, from Peter Sargent and German Peter Lindner. The new Porsche 904 had quickly been homologated to the GT-category with the requisite production of 100 cars, most pre-sold for customer orders. Even with only the old Flat-4 engine, it could still reach 260 kp/h (160 mph). Seven cars were entered for the race: aside from the works car there were entries from the new Racing Team Holland of Erik Hazelhoff Roelfzema and the Scuderia Filipinetti. Jean Kerguen and Jacques Dewes also gave up their Aston Martin (badly damaged at the previous year's race) for Dewes’ new 904. Their only competition in-class was a works MGB entry, driven by British rally ace Paddy Hopkirk. In the GT-1600 class the new Autodelta motorsport division of Alfa Romeo set its first development project to be the Giulia TZ. Now homologated to the GT-category, the uprated 1570cc engine developed 135 bhp with a top speed of 245 kp/h (150 mph). Three cars were entered by the Milanese Scuderia Sant Ambroeus team who had already taken class victories at the Sebring, Targa Florio and Nürburgring races. There was strong support at the Test Weekend on 18–19 April with 34 cars present, although the rain limited performance. Ludovico Scarfiotti put up the fastest time, of 3m43.8 in the new Ferrari 275 P, with John Surtees not far behind with 3m45.9 in his 330 P stablemate.