| 0 | Donohue / Revson | Roger Penske Racing (USA) | | AMC | Javelin | | AMC | T+2.0 |
| 1 | Siffert / Redman | J. W. Engineering (GB) | | Porsche | 917 | K | Porsche | S |
| 2 | Rodriguez / Kinnunen / Redman | J. W. Engineering (GB) | | Porsche | 917 | K | Porsche | S |
| 3 | Ahrens, Jr. / Elford | Porsche Konstruktionen KG (A) | | Porsche | 917 | K | Porsche | S |
| 5 | Cannon / Eaton | Randy's Auto Body Service (USA) | | Lola | T70 | Mk.3B GT | Chevrolet | S |
| 6 | DeLorenzo / Lang | Owens Corning Fibreglass (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.0 |
| 7 | Thompson / Mahler | Owens Corning Fibreglass (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.0 |
| 8 | Johnson / Johnson / Greendyke | Forma Scientific (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.0 |
| 9 | Yenko / Grossman | Mamie Reynolds Gregory (USA) | | Chevrolet | Camaro | I | Chevrolet | GT+2.0 |
| 10 | Hewitt / Ledwith | Hewitt Racing (USA) | Allen Hewitt | Chevrolet | Camaro | I | Chevrolet | T+2.0 |
| 11 | Brock / Dent | Laurel Racing (USA) | | Chevrolet | Camaro | | Chevrolet | T+2.0 |
| 12 | Mitchell / Kemp | Bob Mitchell (USA) | | Chevrolet | Camaro | | Chevrolet | T+2.0 |
| 14 | Cuomo / Gimbel / Lisberg | Ray Cuomo Racing (USA) | | Ford | Mustang | | Ford | T+2.0 |
| 15 | Lowther / Nagel / *Fryer | Bob Fryer (USA) | | Chevrolet | Camaro | I | Chevrolet | T+2.0 |
| 16 | Baker / Baker / *Richards | Ring Free Racing Team (USA) | | Chevron | B16 | | Ford | P |
| 17 | Forester / Hedges | Trevor Graham (GB) | | Ford | GT40 | | Ford | S |
| 18 | Wonder / Cuomo | William Wonder, Inc. (USA) | | Ford | GT40 | | Ford | S |
| 19 | Grant / Heppenstall / Marcus | Auto Enterprises of Chestnut (USA) | Francis C. Grant | Ford | GT40 | | Ford | S |
| 20 | Cluxton / Tatum | North American Racing Team (USA) | | Ferrari | 275 GTB | /C | Ferrari | S |
| 21 | Young / Chinetti, Jr. | North American Racing Team (USA) | | Ferrari | 250 LM | | Ferrari | S |
| 22 | Bucknum / Pickett | North American Racing Team (USA) | | Ferrari | 365 GTB/4 | | Ferrari | S |
| 23 | Adamowicz / Piper | North American Racing Team (USA) | Luigi Chinetti, Jr. | Ferrari | 312 P | Coupe | Ferrari | P |
| 24 | Posey / Parkes | North American Racing Team (USA) | Luigi Chinetti, Jr. | Ferrari | 312 P | Coupe | Ferrari | P |
| 25 | Gurney / Parsons | North American Racing Team (USA) | | Ferrari | 512 S | | Ferrari | S |
| 26 | Vaccarella / Giunti | Ferrari s.p.a. (I) | | Ferrari | 512 S | | Ferrari | S |
| 27 | Schetty / Ickx | Ferrari s.p.a. (I) | | Ferrari | 512 S | | Ferrari | S |
| 28 | Andretti / Merzario / Ickx | Ferrari s.p.a. (I) | | Ferrari | 512 S | | Ferrari | S |
| 30 | Manfredini / Moretti | Squadra Picchio-Rosso (I) | Corrado Manfredini | Ferrari | 512 S | | Ferrari | S |
| 33 | Cevert / Brabham | Matra Sports (F) | | Matra | MS650 | | Matra | P |
| 34 | Beltoise / Pescarolo | Matra Sports (F) | | Matra | MS650 | | Matra | P |
| 37 | Robinson / Kleinpeter / Opert | Fred Opert Racing/Chevron Cars (GB) | Brian Robinson | Chevron | B16 | | Ford | P |
| 38 | Fleming / Johnson | Simone Fleming (USA) | | Fiat | 124 | Sport Coupé | Fiat | T2.0 |
| 39 | Brezinka / Petermann / Bartling | Rainer Brezinka (CDN) | Rainer Brezinka | Porsche | 906 | | Porsche | S |
| 40 | Loomis / Everett / *Harrison | Gregg Loomis (USA) | | Porsche | 906 | E | Porsche | P |
| 43 | Harris / Lewis | William Harris (USA) | | Austin-Healey | Sprite | | BMC | P |
| 44 | Pieper / McDaniel / Krogsund | H.R.H. Corp. (USA) | | Deserter | GS | | VW | P |
| 46 | Darden / Matzen | Jack Haywood (USA) | | Shelby | GT350 | | Ford | GT+2.0 |
| 47 | Bandy / Stevenson / Williams | Sports Motors, Inc. (USA) | | Lotus | 47 | | Ford | S |
| 48 | Taylor / Sheldon | Del Taylor (USA) | | Alfa Romeo | 1750 GTV | | Alfa Romeo | T2.0 |
| 51 | Fernandez / Juncadella | Escuderia Montjuich (E) | | Porsche | 908/02 | | Porsche | P |
| 52 | Dean / Gregg | Tony Dean (GB) | | Porsche | 917 | K | Porsche | S |
| 53 | Laine / van Lennep | Racing Team AAW (FIN) | | Porsche | 908/02 | K | Porsche | P |
| 54 | Pairetti / De Cadenet / Del Río | Juan Manuel Fangio (RA) | | Porsche | 908/02 | | Porsche | P |
| 55 | Kearney / Roberts / Purdy | Donald E. Kearney (USA) | | Datsun | 510 | PL | Datsun | T2.0 |
| 66 | Matthews / Sesslar / Weaver | H. Edward Mathews (USA) | | Ford | Mustang | | Ford | T+2.0 |
| 70 | Patterson / Sanford | Sportade Racing Team (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 71 | Walle / Speakman | Walle Enterprises (USA) | | TVR | Vixen | | Ford | P |
| 72 | Duval / Bailey | Jacques Duval (CDN) | | Porsche | 911 | T/R | Porsche | GT2.0 |
| 73 | Rinzler / Reynolds | Ring Free Racing Team (USA) | | Austin-Healey | Sprite | | BMC | P |
| 74 | Meaney / Wright / Bean | Ralph Meaney (USA) | | Porsche | 911 | S | Porsche | GT2.0 |
| 75 | Hochreuter / Bytzek | Friedrich Hochreuter (CDN) | | Porsche | 911 | | Porsche | GT2.0 |
| 76 | Addison / Dahm | Scotty Addison (USA) | | Porsche | 911 | Coupé | Porsche | GT2.0 |
| 77 | Jennings / Tullius | Toad Hall Racing (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 78 | Belperche / Lilly / Pickett | Waldron Motors (USA) | | MG | B | | BMC | GT2.0 |
| 79 | Waldron / Lanier / Barros | Waldron Motors (USA) | | MG | B | | BMC | GT2.0 |
| 83 | Collins / Wilson | Dr. Vince Collins (USA) | | Ford | Mustang | | Ford | T+2.0 |
| 84 | Brown / Marcus / Sandman | H.C.A.S., Inc. (USA) | | BMW | 2002 | | BMW | T2.0 |
| 85 | Whitaker / Krebs / Eckoff | Robert Whitaker (USA) | | Volvo | 122 | S | Volvo | T2.0 |
| 86 | Mollin / Riley | Arthur Mollin Racing (USA) | | Volvo | 122 | S | Volvo | T2.0 |
| 88 | Batchin / Oest | Auto Enterprises of Chestnut (USA) | | Lancia | Fulvia | HF | Lancia | T2.0 |
| 89 | Gottlob / Dooley | Cliff Gottlob (USA) | Cliff Gottlob | Chevrolet | Corvette | | Chevrolet | GT+2.0 |
| 90 | Costanzo / Heinz | Or Costanzo (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.0 |
| 91 | Barker / Greenwood / Hoffman | Auto Research Eng. (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.0 |
| 92 | Mims / Corwin / Pipen | Flem-Cor Enterprises (USA) | | Chevrolet | Camaro | Z28 | Chevrolet | T+2.0 |
| 93 | Harrell / Magnor | Redline Engineering, Inc. (USA) | | Ford | Mustang | | Ford | T+2.0 |
| 94 | Cummings / Stumes | Susan T. Cummings (USA) | | Shelby | GT350 | | Ford | GT+2.0 |
| 95 | Brockman / Tremblay | Bruce Behrens Racing (USA) | | Chevrolet | Camaro | I Z28 | Chevrolet | T+2.0 |
| 96 | Gimondo / Dietrich | Takondo Racing (USA) | | Chevrolet | Camaro | I Z28 | Chevrolet | T+2.0 |
| 97 | Elliott / Gwynne | Preston Hood Chevrolet (USA) | | Chevrolet | Camaro | I Z28 | Chevrolet | T+2.0 |
| 98 | Mastandrea / Drolet / Rodgers | Norberto Mastandrea (USA) | | Chevrolet | Camaro | I | Chevrolet | T+2.0 |
| T1 | Cevert / Brabham / Beltoise / Pescarolo | Matra Sports (F) | | Matra | MS630 | /650 | Matra | P |
| T | Rodriguez / Kinnunen / Siffert | J. W. Engineering (GB) | | Porsche | 917 | K | Porsche | S |