| 1 | Oliver / Ickx | J. W. Automotive Eng. (GB) | | Ford | GT40 | | Ford | S5.0 |
| 2 | Hobbs / Hailwood | J. W. Automotive Eng. (GB) | | Ford | GT40 | | Ford | S5.0 |
| 4 | McDaniel / Pieper / Scott | HRH Corp. (USA) | | Zink | Z8 | VSR | VW | P2.0 |
| 5 | Grossman / Dini | Randy's Auto Body (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 6 | Donohue / Parsons / *Bucknum | Roger Penske Racing (USA) | | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 7 | *Wonder / *Cuomo | William Wonder, Inc. (USA) | | Ford | GT40 | | Ford | S5.0 |
| 8 | Leslie / Motschenbacher | American International Racing (USA) | James Garner | Lola | T70 | Mk.3 GT | Chevrolet | S5.0 |
| 9 | Patrick / Jordan | American International Racing (USA) | James Garner | Lola | T70 | Mk.3 GT | Chevrolet | S5.0 |
| 11 | Yenko / Guldstrand | Best Photo Serv. Inc. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 14 | Everett / Johnson / Coleman | Fine Grinding Co. (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 15 | Bock / Dent | Larry Drover (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 16 | Rafferty / Gearhart / Wisler | Rafferty Racing | Wedge Rafferty | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 17 | McClain / Costanzo | David H. McClain (USA) | David H. McClain | Chevrolet | Camaro | I Z28 | Chevrolet | T5.0 |
| 18 | Carter / Adams | Maurice Carter Chevrolet (CDN) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 19 | Buckley / Cooper | Bud Moore | | Mercury | Cougar | I | Ford | T5.0 |
| 20 | Adamowicz / Jennings / Wetanson | P.A.R.T. (USA) | Herb Wetanson | Porsche | 911 | T | Porsche | GT2.0 |
| 21 | Netterstrom / Kelly | P.A.R.T. (USA) | Porsche America Racing Team | Porsche | 911 | | Porsche | T2.0 |
| 22 | Bailey / Locke / Downs | P.A.R.T. (USA) | Porsche America Racing Team | Porsche | 911 | | Porsche | T2.0 |
| 24 | Servoz-Gavin / Pescarolo | Matra-Sports (F) | | Matra | M630 | | Matra | P3.0 |
| 25 | Dibos / Calabattisti | Dibos Ch. (PE) | | Alfa Romeo | T33/2 | | Alfa Romeo | P3.0 |
| 26 | Titus / Ward | Jon Ward Racing Ent. (USA) | | Pontiac | Firebird | | Pontiac | T5.0 |
| 28 | Corwin / Manner / Baird | Flem-Cor Ent. (USA) | Jim Corwin | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 32 | Rose / Richards / *Hill | Harold Rose (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 33 | McComb / Dooley | John McComb Racing (USA) | | Ford | Mustang | | Ford | T5.0 |
| 36 | Pickett / Downs / *Tullius | Dr. Wilbur Pickett (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 37 | Strickler / Wherrell | Richard E. Crebs (USA) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | T2.0 |
| 38 | Merello / Maglioli / Alvarez | Team Raceco of Miami (USA) | | Ferrari | 250 LM | | Ferrari | S5.0 |
| 39 | Kleinpeter / Gunn / Beatty | Raceco of Miami (USA) | | Chevron | B8 | | BMW | S2.0 |
| 40 | Kolb / Biscaldi | North American Racing Team (USA) | | Ferrari | Dino 206 S | Coupé | Ferrari | P2.0 |
| 41 | Posey / Rodriguez | North American Racing Team (USA) | | Ferrari | 275 GTB | /C | Ferrari | GT5.0 |
| 43 | Wright / Craine | Gary Wright (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 45 | Waltman / Bird | Scuderia Autosport (USA) | George Waltman | Osca | GT | 1600 | Maserati | S2.0 |
| 46 | Debo / Parkerson | Bud Boles Racing (USA) | | Triumph | TR4 | | Triumph | GT5.0 |
| 47 | Williamson / Drolsom | Dr. Harold Williamson (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 48 | Wicky / Garant | Wicky Racing Team (CH) | André Wicky | Porsche | 911 | T | Porsche | GT2.0 |
| 49 | Crebs / Whitaker | Richard E. Crebs (USA) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | T2.0 |
| 50 | Siffert / Herrmann | Porsche System Engineering (D) | | Porsche | 908 | Coupe | Porsche | P3.0 |
| 51 | Attwood / Buzzetta | Porsche System Engineering (D) | | Porsche | 908 | Coupe | Porsche | P3.0 |
| 52 | Elford / Redman | Porsche System Engineering (D) | | Porsche | 908 | Coupe | Porsche | P3.0 |
| 53 | Schütz / Mitter / Attwood | Porsche System Engineering (D) | | Porsche | 908 | Coupe | Porsche | P3.0 |
| 54 | Stommelen / Ahrens, Jr. | Porsche System Engineering (D) | | Porsche | 908 | Coupe | Porsche | P3.0 |
| 55 | Gammon / Mummery / *Smith | Waldron Motors (USA) | Chris Waldron | MG | B | | BMC | GT2.0 |
| 56 | Harris / Waldron / Scott | Waldron Motors (USA) | Chris Waldron | MG | B | | BMC | GT2.0 |
| 57 | Heinz / Moerwald | David Heinz Imports (USA) | | MG | B | | BMC | GT2.0 |
| 58 | Soler-Roig / Lins | Escuderia Nacional CS (E) | Alex Soler-Roig | Porsche | 907 | | Porsche | P3.0 |
| 59 | Gregg / Axelsson | Brumos Porsche (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 60 | Norinder / Bonnier / *Servoz-Gavin | Sportscars Unlimited Switzerland (CH) | Ulf Norinder | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 60T | | Sportscars Unlimited Switzerland (CH) | Ulf Norinder | Lola | T70 | Mk.3 GT | Chevrolet | S5.0 |
| 61 | Gregory / Broström | Sportscars Unlimited Switzerland (CH) | | Porsche | 910 | | Porsche | S2.0 |
| 62 | Bartling / Hochreuter / Brezinka / *Petermann | Rainer Brezinka (CDN) | Rainer Brezinka | Porsche | 906 | | Porsche | S2.0 |
| 66 | DeLorenzo / Lang | Owens-Corning Fiberglass Troy Promotions (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+5.0 |
| 67 | Thompson / Harrell / DeLorenzo | Owens-Corning Fiberglass Troy Promotions (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+5.0 |
| 68 | Duval / Nicholas / *Samson | Jacques Duval (CDN) | | Porsche | 911 | T/R | Porsche | GT2.0 |
| 69 | Lowther / Esseks / Dominianni | Robert D. Esseks (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 72 | Hagan / McVeigh / Gillebard | Lafayette Speed Center (USA) | | Mercury | Cougar | I | Ford | T5.0 |
| 73 | Opert / Sanford | Fred Opert Racing (USA) | Fred Opert | Porsche | 911 | | Porsche | T2.0 |
| 77 | Gifford / Campbell | Williams Racing Ent. (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 79 | Riley / Mollin | Arthur Mollin Racing (USA) | | Volvo | 122 | S | Volvo | T2.0 |
| 81 | Pryor / Marina | Auto of Italy, Inc. (USA) | Anatoly Arutunoff | Alfa Romeo | Giulia Sprint Speciale | | Alfa Romeo | GT2.0 |
| 83 | Baker / Baker / Richards | MacMillan Ring Free (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| 86 | Harrison / Ryan | RBM Motors (USA) | Jack Ryan | Porsche | 911 | S | Porsche | T2.0 |
| 88 | Grant / Oest / Batchin | Auto Enterprise of ChestnutHills (USA) | | Lancia | Fulvia | HF | Lancia | GT2.0 |
| 89 | James Hall | LeVerne Hartje | | Dodge | Dart | | Dodge | T5.0 |
| 91 | Mastandrea / Silvers / Ormes | Mar Shipping Co. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 92 | Jowett, Jr. / Fisher | Wilton T. Jowett, Sr. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 93 | Cline / Pickering | Richard Cline | | Triumph | GT6 | | Triumph | GT2.0 |
| 96 | Drolet / Tremblay / Gimondo / Belperche | Zorian Productions, Ltd. (USA) | | Chevrolet | Corvette | C2 | Chevrolet | GT+5.0 |
| 97 | Maglioli / Pinto | Algar Enterprises (USA) | | Lancia | Fulvia | Sport | Lancia | P2.0 |
| 98 | Hollander / Clark / Marsula | Algar Enterprises (USA) | | Lancia | Fulvia | Sport | Lancia | P2.0 |
| 99 | Robson / Rodgers | Coguna Motors (USA) | Richard Robson | Jaguar | E-type | | Jaguar | GT5.0 |