| 1 | DeLorenzo / Thompson / *McConkey | Troy Promotions, Inc. (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+5.0 |
| 2 | Lang / Hufstader | Troy Promotions, Inc. (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 3 | Lowther / Esseks / Dominianni | Robert D. Esseks (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 4 | Costanzo / Heinz | Or Costanzo (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 5 | Yenko / Grossman / *Guldstrand | Best Photo Service (USA) | | Chevrolet | Camaro | I Z28 | Chevrolet | GT+5.0 |
| 6 | Davis / Madray / Madray / *Davis | Herbert R. Madray (USA) | | Ford | Mustang | | Ford | T5.0 |
| 7 | Rainville / Pettey | Argento Racing Organization (USA) | | Ford | Mustang | | Ford | T5.0 |
| 8 | van Beuren, Jr. / Perez Gama / Novoa | Fred Van Beuren (MEX) | | Pontiac | Firebird | | Pontiac | T5.0 |
| 9 | Bucknum / Donohue | Roger Penske Racing Enterprises (USA) | | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 10 | Patrick / Jordan | American International Racing, Inc. (USA) | James Garner | Lola | T70 | Mk.3 GT | Chevrolet | S5.0 |
| 11 | Motschenbacher / Leslie | American International Racing, Inc. (USA) | James Garner | Lola | T70 | Mk.3 GT | Chevrolet | S5.0 |
| 14 | Norinder / Bonnier | Sportscars Switzerland (CH) | Ulf Norinder | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 16 | Stevens / Barg | Richard Stevens (CDN) | Richard Stevens | Chevrolet | Camaro | I Z28 | Chevrolet | T5.0 |
| 17 | Gimondo / Tremblay | Bruce Behrens Racing Enterprises (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 18 | Jowett, Jr. / Tullius | Wilton T. Jowett, Srov. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 19 | Carter / Adams | Maurice Carter Chevrolet (CDN) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 20 | McClain / Kerney | David H. McClain (USA) | David H. McClain | Chevrolet | Camaro | I Z28 | Chevrolet | T5.0 |
| 21 | Dent / Bock | Larry Drover, (Laural Racing) (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 22 | Oliver / Ickx | J. W. Automotive Engineering Ltd. (GB) | | Ford | GT40 | | Ford | S5.0 |
| 23 | Hobbs / Hailwood | J. W. Automotive Engineering Ltd. (GB) | | Ford | GT40 | | Ford | S5.0 |
| 24 | Grant / Oest | Auto Enterprizes (USA) | Francis C. Grant | Ford | GT40 | | Ford | S5.0 |
| 25 | Amon / Andretti | Ferrari S.P.A. SEFAC (I) | Enzo Ferrari | Ferrari | 312 P | | Ferrari | P3.0 |
| 26 | Rodriguez / Parsons | N.A.R.T. (USA) | | Ferrari | 250 P | | Ferrari | P3.0 |
| 27 | Stommelen / Buzzetta / Ahrens, Jr. | Porsche System Engineering Ltd. (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 28 | Herrmann / Ahrens, Jr. / Stommelen | Porsche System Engineering Ltd. (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 29 | Mitter / Schütz | Porsche System Engineering Ltd. (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 30 | Elford / Attwood | Porsche System Engineering Ltd. (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 31 | Siffert / Redman | Porsche System Engineering Ltd. (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 31T | Larrousse / Maglioli | Porsche System Engineering (D) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 32 | Casoni / de Adamich / *Surtees | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 33 | Vaccarella / Bianchi | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 34 | Galli / Giunti / *Casoni | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 35 | Hedges / Hopkirk | British Leyland Motor Corporation (GB) | | MG | C | GT | BMC | P3.0 |
| 36 | Brack / Hill | British Leyland Motor Corporation (GB) | | MG | C | | BMC | P3.0 |
| 37 | Rodriguez / Kolb / *Posey | N.A.R.T. (USA) | | Ferrari | Dino 206 S | Coupé | Ferrari | P2.0 |
| 38 | Posey / Dini / *Rodriguez | N.A.R.T. (USA) | | Ferrari | Dino 206 GT | | Ferrari | P2.0 |
| 41 | DeAmbadgio / Trevale / *Sandoval | Escuderia Manana (YV) | | Alfa Romeo | 1300 GTA Junior | | Alfa Romeo | T2.0 |
| 43 | Heppenstall / Brown | LeHigh Acres (USA) | | Heppenstall | Special | | VW | P2.0 |
| 44 | Soler-Roig / Lins | Escuderia Nacional C.S. (E) | | Porsche | 907 | | Porsche | P3.0 |
| 45 | Baker / Smothers | Smothers Brothers Racing Team (USA) | | Porsche | 906 | E | Porsche | P2.0 |
| 46 | Capriles / Atencio / *Maratos | Escuderia Manana (YV) | | Porsche | 906 | E | Porsche | P2.0 |
| 47 | Bailey / Locke / *Jennings | P.A.R.T. (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 48 | Rahal / Stroh / Wise | Nationwide of Chicago Food Brothers, Inc. (USA) | | Porsche | 906 | | Porsche | S3.0 |
| 49 | Rosen / Morrell | Dr. Merv Rosen (USA) | Merwin Rosen | Porsche | 906 | | Porsche | S3.0 |
| 50 | Duval / Nicholas | Grand Prix Motor Oil (CDN) | | Porsche | 911 | T/R | Porsche | GT2.0 |
| 51 | Loomis / Harrison / Ryan | RBM Motors (USA) | Jack Ryan | Porsche | 911 | S | Porsche | GT2.0 |
| 52 | Larrousse / Wicky / Sage | Wicky Racing Team (CH) | André Wicky | Porsche | 911 | T | Porsche | GT2.0 |
| 53 | Pickett / Gregg | Wilbur Pickett (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 54 | Sanford / Opert | Fred Opert (USA) | Fred Opert | Porsche | 911 | | Porsche | T2.0 |
| 57 | Maglioli / Kleinpeter / Beatty | Raceco (USA) | | Chevron | B8 | | BMW | S3.0 |
| 58 | Hugus / Dietrich / Nearburg | Elsco Corporation (USA) | | BMW | 2002 | | BMW | T2.0 |
| 59 | Drolet / Smith | Elsco Corporation (USA) | | BMW | 2002 | | BMW | T2.0 |
| 60 | Brown / Marcus | Jim Cooke Buick & Opel (USA) | | Opel | Kadett | Rallye | Opel | T2.0 |
| 61 | Samm / Parks / Colgate | Gerry Racing Enterprise, Inc. (USA) | | Lotus | 47 | | Ford | P2.0 |
| 62 | Blackburn / Truitt | British Leyland Motor Corporation (GB) | | MG | B | GT | BMC | GT2.0 |
| 63 | Gammon / Mummery / Houghton | Waldron Motors (USA) | | MG | B | | BMC | GT2.0 |
| 64 | Waldron / Scott / Donley | Waldron Motors (USA) | | MG | B | | BMC | GT2.0 |
| 65 | Maglioli / Pinto | Algar Enterprises, Inc. (USA) | | Lancia | Fulvia | Sport | Lancia | P2.0 |
| 66 | Ireland / Tillson / Hanna | Algar Enterprises, Inc. (USA) | | Lancia | Fulvia | 1.6 HF Coupé | Lancia | P2.0 |
| 67 | Boye / Shirey | Competition Components (USA) | | Beach | Mk.4 | B | VW | P2.0 |
| 68 | Scott / McDaniel / Pieper | H.R.H. Corp. (USA) | | Zink | Z8 | VSR | VW | P2.0 |
| 69 | Smith / Lilly / Pickett / *Howard | John F. Howard (USA) | | Lotus | Europa | | Renault | GT2.0 |
| 71 | Baker / Richards / Baker | Ring Free Oil Racing Team (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| 72 | Guthrie / Mims / Engeman | Ring Free Oil Racing Team (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| 73 | Cameron / Kemmerer / *Phillips | Arthur Tuckerman (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| 84 | Drolsom / Williamson | Dr. Harold Williamson (USA) | | Porsche | 911 | | Porsche | T2.0 |
| 85 | Crebs / Strickler / Whitaker | Richard Crebs (USA) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | T2.0 |
| 88 | Blessing / Cummings / Stumes | Donald C. Cummings (USA) | | Shelby | GT350 | | Ford | GT5.0 |
| 90 | Netterstrom / Jennings / Downs | P.A.R.T. (USA) | Bruce Jennings | Porsche | 911 | | Porsche | GT2.0 |
| 93 | Fisher / Adams | Todco Racing Canada Ltd. (CDN) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 94 | Ormes / Mastandrea | Norberto Mastandrea (Freeport Bahama Racing Team) (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 98 | Polimeni / Theall | George W. Sanderson (USA) | | Volvo | PV 544 | | Volvo | T2.0 |
| 99T | Colgate / Parks / *Hopkirk / *Hedges / *Brack / *Hill / *Truitt / *Blackburn | Gerry Racing Enterprise, Inc. (GB) | | MG | B | | BMC | GT2.0 |