| 1 | McLaren / Andretti | Ford Motor Company (USA) | | Ford | Mk IV | | Ford | P+2.0 | Class 13 |
| 2 | Foyt / Ruby | Ford Motor Company (USA) | | Ford | Mk II | B | Ford | P+2.0 | Class 13 |
| 4 | Welch / Wintersteen | Roger Penske (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+5.0 | Class 13 |
| 5 | Johnson / Jennings / *Hall | Chaparral Cars (USA) | | Chaparral | 2D | | Chevrolet | P+2.0 | Class 13 |
| 6 | Spence / Hall / *Hill | Chaparral Cars (USA) | | Chaparral | 2F | | Chevrolet | P+2.0 | Class 13 |
| 8 | Yenko / Morgan | Sunray DX Oil Co. (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+5.0 | Class 13 |
| 9 | Costanzo / Guy / McClain | Or. Costanzo (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+5.0 | Class 13 |
| 11 | Thompson / Lowther | J. W. Engineering, Ltd. (GB) | Grady Davis | Ford | GT40 | | Ford | S5.0 | Class 12 |
| 12 | McCluskey / Fulp | John R. Fulp (USA) | John Fulp | Lola | T70 | Mk.2 | Chevrolet | P+2.0 | |
| 14 | Wonder / Caldwell | William Wonder (USA) | | Ford | GT40 | | Ford | S5.0 | Class 12 |
| 15 | Nagel / Heppenstall / Seeley | Howmet Corporation (USA) | | Howmet | Sprint | | Ford | P+2.0 | Class 12 |
| 16 | Brooker / Yeager | Brad Brooker (USA) | | Shelby | GT350 | R | Ford | GT5.0 | Class 12 |
| 17 | Grossman / McNamara | Autosport International (AUS) | Patrick McNally | Ford | GT40 | | Ford | S5.0 | Class 12 |
| 18 | van Beuren, Jr. / Jett | Dos Caballos Racing Team (MEX) | Freddy van Beuren | Shelby | GT350 | R | Ford | GT5.0 | Class 12 |
| 19 | Vaccarella / Maglioli | Brescia Corse Team (I) | | Ford | GT40 | | Ford | S5.0 | Class 12 |
| 20 | Piper / Attwood | David Piper Racing (GB) | David Piper | Ferrari | 365 P2 | /3 | Ferrari | P+2.0 | Class 12 |
| 21 | Robson / Rodgers / Buchman | Richard Robson (USA) | Richard Robson | Jaguar | E-type | | Jaguar | GT5.0 | Class 12 |
| 23 | Rodriguez / de la Chica | Federico de la Chica (MEX) | | Ferrari | 250 LM | | Ferrari | P+2.0 | Class 12 |
| 25 | McCluggage / Windridge | Northern Vermont Racing Team (USA) | | Ferrari | 275 GTB | /4 Spyder | Ferrari | GT5.0 | Class 12 |
| 27 | Kelly / Tharin / Pickett / *Canada | Joseph C. Hines (USA) | | Triumph | TR4 | | Triumph | GT3.0 | Class 10 |
| 28 | Vega / Witt / Kingham | Milo Vega (USA) | | Triumph | TR4 | A | Triumph | GT3.0 | Class 10 |
| 29 | Burr / Owen | Tim Burr (USA) | Tim Burr | Triumph | TR4 | A | Triumph | GT3.0 | Class 10 |
| 30 | Hopkirk / Hedges | British Motor Corp. (GB) | | MG | B | GT | BMC | P+2.0 | Class 10 |
| 32 | Rodriguez / Guichet | Scuderia Ambroeus (I) | Pedro Rodriguez | Ferrari | Dino 206 S | Coupé | Ferrari | P2.0 | Class 9 |
| 33 | Williams / Casoni | Scuderia Brescia Corse (I) | | Ferrari | Dino 206 S | | Ferrari | P2.0 | Class 9 |
| 34 | Klass / Müller | Scuderia Filipinetti (CH) | Georges Filipinetti | Ferrari | Dino 206 S | | Ferrari | P2.0 | Class 9 |
| 35 | Crawford / Kolb | NART (USA) | Fred J. Baker | Ferrari | Dino 206 S | | Ferrari | P2.0 | Class 9 |
| 36 | Patrick / Mitter | Porsche Auto (D) | | Porsche | 910 | | Porsche | P2.0 | Class 9 |
| 37 | Siffert / Herrmann | Porsche Auto (D) | | Porsche | 910 | | Porsche | P2.0 | Class 9 |
| 38 | Buzzetta / Gregg | Porsche Auto (D) | | Porsche | 906 | | Porsche | P2.0 | Class 9 |
| 39 | Schütz / van Lennep / Stommelen | Porsche Auto (D) | | Porsche | 906 | E | Porsche | P2.0 | Class 9 |
| 40 | Steinemann / Spoerry | Squadra Tartaruga (CH) | | Porsche | 906 | LH | Porsche | P2.0 | Class 9 |
| 41 | Greger / Besier | Sepp Greger (D) | | Porsche | 911 | Coupé | Porsche | GT2.0 | Class 9 |
| 42 | Cannon / Hugus | Ed Hugus (USA) | | Porsche | 906 | E | Porsche | S2.0 | Class 9 |
| 43 | Groggins / Bailey / Kelly | B & B Motors (USA) | | Porsche | 356 | C 1600 SC | Porsche | S2.0 | Class 9 |
| 44 | Kolb / Baker / Cutler | Baker Racing Team (USA) | | Porsche | 906 | E | Porsche | S2.0 | Class 9 |
| 45 | Ryan / Bencker | RBM Motors (USA) | Jack Ryan | Porsche | 911 | S | Porsche | GT2.0 | Class 9 |
| 46 | Kirby / Johnson | Bursch Tuned Exhaust (USA) | Rob Kirby | Porsche | 911 | S | Porsche | GT2.0 | Class 9 |
| 47 | Drolsom / Campbell | George Drolsom (USA) | | Porsche | 904 | GTS | Porsche | S2.0 | Class 9 |
| 48 | Rhodes / Mäkinen | British Motor Corp. (GB) | | MG | B | | BMC | GT2.0 | Class 9 |
| 49 | Magwood / Gray | Canadian Auto Racing Team (CDN) | | MG | B | | BMC | GT2.0 | Class 9 |
| 51 | Siegmund / Liebl | Viper Racing, Inc. (USA) | | Volvo | P1800 | | Volvo | S2.0 | Class 9 |
| 53 | Kleinpeter / Rothschild | Competition Components, Inc. (USA) | | Beach | Mk.8 | | | P2.0 | Class 8 |
| 54 | Arutunoff / Pryor | A.R.C.O., Inc. (USA) | Anatoly Arutunoff | Alfa Romeo | Giulia SV | | Alfa Romeo | GT2.0 | Class 8 |
| 55 | Waltman / Cone | George Waltman (USA) | | Osca | GT | 1600 | Maserati | S1.6 | Class 8 |
| 56 | Cella / Maglioli / Munari | H.F. Squadra (I) | | Lancia | Fulvia | HF | Lancia | P2.0 | Class 7 |
| 57 | Drolet / Taylor | Baker Racing Team (USA) | | Alpine | A110 | | Renault | S1.3 | Class 7 |
| 58 | Baird / Enever / Poole | Donald Healey Motor Co. (GB) | | Austin-Healey | Sprite | Le Mans | BMC | P2.0 | Class 7 |
| 59 | Baker / Aaltonen | Donald Healey Motor Co. (GB) | | Austin-Healey | Sprite | Le Mans | BMC | P2.0 | Class 7 |
| 60 | Kondracki / Pickering | Richard G. Kondracki (USA) | | Triumph | Spitfire | | Triumph | GT1.3 | Class 6 |
| 61 | Brown / Hanna | Howard Hanna (USA) | | Matra | Djet | 5S | Renault | GT1.3 | Class 6 |
| 62 | Engeman / Guthrie | Ring-Free Oil Racing Team (USA) | | Matra | Djet | 5S | Renault | GT1.3 | Class 6 |
| 63 | Dietrich / Mims | Ring-Free Oil Racing Team (USA) | | ASA | 411 | | ASA | P2.0 | Class 8 |
| 65 | de Adamich / Zeccoli | Autodelta (I) | | Alfa Romeo | T33 | | Alfa Romeo | P2.0 | Class 9 |
| 66 | Bussinello / Andrey | Autodelta (I) | | Alfa Romeo | T33 | | Alfa Romeo | P2.0 | Class 9 |
| 68 | Smith / Turner / *Fretina | Major Billy Turner (USA) | Billy Turner | Austin-Healey | Sprite | Mk I | BMC | S1.3 | Class 7 |
| 69 | Jowett, Jr. / Mouat / Cardwell | Wilton T. Jowett (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 | |
| 70 | West / Ausburn / Allison | Treadwell Ford Racing Team (USA) | Roger West | Shelby | GT350 | R | Ford | GT5.0 | Class 12 |
| 71 | Richards / Cuomo / Norwood | Ring-Free Oil Racing (USA) | | Shelby | GT350 | | Ford | GT5.0 | Class 12 |
| 72 | Opert / Pauley / Bowman / Cutler / *Ziereis | Valvoline-Opert Racing Team (USA) | Fred Opert | Porsche | 911 | S | Porsche | GT2.0 | Class 9 |