| 1 | Titus / Bucknum | Shelby Racing (USA) | Carroll Shelby | Ford | Mustang | | Ford | TA+2.0 |
| 2 | Moffat / Kwech / Follmer | Shelby Racing (USA) | Carroll Shelby | Ford | Mustang | | Ford | TA+2.0 |
| 3 | McDaniel / Sullivan | HRH Corp. (USA) | | Porsche | 911 | R | Porsche | P |
| 4 | Moore / Murphy | HRH Corp. (USA) | | Chevrolet | Camaro | I | Chevrolet | TA+2.0 |
| 5 | Sherk / Diehl | Bud Sherk Auto Fair (USA) | | Dodge | Dart | | Dodge | TA+2.0 |
| 6 | Donohue / Johnson / Fisher | Roger Penske Racing Ent. (USA) | Roger Penske | Chevrolet | Camaro | I Z28 | Chevrolet | TA+2.0 |
| 7 | Hagan / McVeigh / Gillebard | Billy Hagan (USA) | | Mercury | Cougar | I | Ford | TA+2.0 |
| 8 | Ickx / Redman | J. W. Automotive Eng. (GB) | | Ford | GT40 | | Ford | S |
| 9 | Hawkins / Hobbs | J. W. Automotive Eng. (GB) | | Ford | GT40 | | Ford | S |
| 10 | Lanfranchi / Konig | Nomad Cars (GB) | | Nomad | Mk.1 | | Ford | P |
| 11 | Martland / Classick | Chevron Cars (GB) | | Chevron | B6 | | BMW | P |
| 12 | Vestey / Pike / Ridgway | Paul Vestey Racing (GB) | | Ferrari | 250 LM | | Ferrari | S |
| 13 | McLaren / Hall | Samato, Ltd. (Smokey Yunick) (EC) | | Chevrolet | Camaro | I | Chevrolet | TA+2.0 |
| 14 | Everett / Jennings / Bailey | Bob Holbert's Garages (USA) | | Porsche | 911 | S | Porsche | TA2.0 |
| 15 | Grossman / Dini | Randy's Auto Body (USA) | | Ford | Mustang | | Ford | TA+2.0 |
| 17 | Mollin / Cone | Arthur Mollin Racing Ent. (USA) | | TVR | Grantura | Mk IV | BMC | GT |
| 18 | Nelson / Hailwood | Edward Nelson Racing (GB) | Edward Nelson | Ford | GT40 | | Ford | S |
| 19 | Keenan / Torpy / Sutter | D-K Racing (USA) | | Chevrolet | Corvette | | Chevrolet | S |
| 20 | Schütz / Vaccarella | Autodelta S.p.a. (I) | | Alfa Romeo | T33/2 | | Alfa Romeo | P |
| 21 | Galli / Giunti | Autodelta S.p.a. (I) | | Alfa Romeo | T33/2 | | Alfa Romeo | P |
| 22 | Casoni / Biscaldi / Zeccoli | Autodelta S.p.a. (I) | | Alfa Romeo | T33/2 | | Alfa Romeo | P |
| 22T | Mario Casoni | Autodelta S.p.a. (I) | | Alfa Romeo | T33/2 | | Alfa Romeo | P |
| 23 | Andretti / Bianchi | Autodelta S.p.a. (I) | | Alfa Romeo | T33/2 | | Alfa Romeo | P |
| 24 | Cella / Zeccoli / Biscaldi | Autodelta S.p.a. (I) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | TA2.0 |
| 25 | Pinto / Dini | Autodelta S.p.a. (I) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | TA2.0 |
| 26 | Maglioli / Andersson / Baghetti | Algar Enterprises (USA) | | Lancia | Fulvia | Sport | Lancia | P |
| 27 | Baghetti / Facetti / Andersson | Algar Enterprises (USA) | | Lancia | Fulvia | HF | Lancia | P |
| 28 | Ross / Pelouze | Corvette Racing Associates (USA) | | Chevrolet | Corvette | C2 | Chevrolet | GT |
| 29 | Revson / Yenko | DX Sunray Oil Co. (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT |
| 30 | Thompson / DeLorenzo | DX Sunray Oil Co. (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT |
| 31 | Grant / Morgan | DX Sunray Oil Co. (USA) | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT |
| 32 | Ryan / Harrison | RBM Motors (USA) | Jack Ryan | Porsche | 911 | S | Porsche | TA2.0 |
| 34 | Gunn / Ortega / Merello | Raceco-Miami (USA) | | Ferrari | 250 LM | | Ferrari | S |
| 35 | George Waltman | Aztec Motor Racing (USA) | | Morgan | Plus 4 | | Triumph | GT |
| 36 | Pickett / Bean / Bencker | Dr. Wilbur Pickett (USA) | | Porsche | 911 | S | Porsche | TA2.0 |
| 37 | Wonder / Cuomo | William Wonder, Inc. (USA) | | Ford | GT40 | | Ford | S |
| 41 | Rushin / Harris / Waldron | Thomas Harris (USA) | | MG | B | | BMC | GT |
| 42 | Rodgers / Robson / Buchman | Coquina Motors (USA) | Richard Robson | Jaguar | E-type | | Jaguar | GT |
| 43 | Schwenker / Dube / Kelder | Cannons Auto Service (USA) | | Triumph | TR4 | A | Triumph | GT |
| 44 | Guldstrand / Leslie / Patrick / Jordan | American International Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT |
| 45 | Patrick / Jordan / Caplan | American International Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT |
| 46 | Payne-Herbert / Miller / Walton | WROD Radio (USA) | Grant Miller | Porsche | 356 | B 2000 GS Carrera 2 | Porsche | GT |
| 47 | Vega / Witt / *Cameron | John Cameron (USA) | | Triumph | TR4 | A | Triumph | GT |
| 48 | Poole / Stott / Morehead / *Harris | Doyle Poole (USA) | | Triumph | TR4 | A | Triumph | GT |
| 49 | Maxwell / Martin | Ike A. Maxwell, Jr. (USA) | | Volvo | 122 | S | Volvo | TA2.0 |
| 51 | Schlesser / Buzzetta | Porsche Works Team (D) | | Porsche | 907 | LH | Porsche | P |
| 52 | Siffert / Herrmann / *Mitter | Porsche Works Team (D) | | Porsche | 907 | LH | Porsche | P |
| 53 | Mitter / Stommelen / *Herrmann | Porsche Works Team (D) | | Porsche | 907 | LH | Porsche | P |
| 54 | Elford / Neerpasch / Stommelen / Siffert / Herrmann | Porsche Works Team (D) | | Porsche | 907 | LH | Porsche | P |
| 55 | Steinemann / Spoerry | Squadra Tartaruga (CH) | | Porsche | 907 | LH | Porsche | P |
| 56 | Netterstrom / Kelly / Sabel | Ship Sharpe Maintenance (USA) | John Kelly | Porsche | 911 | | Porsche | TA2.0 |
| 57 | Cline / Pickering | Richard P. Cline | | Triumph | GT6 | | Triumph | GT |
| 58 | Andrews, Jr. / Kondracki | Richard Cline (USA) | | Triumph | Spitfire | | | GT |
| 59 | Gregg / Axelsson | Brumos Porsche (USA) | | Porsche | 911 | | Porsche | TA2.0 |
| 61 | Hanrioud / Garant | J. P. Hanrioud (F) | | Porsche | 911 | S | Porsche | GT |
| 64 | Taylor / Pratt / Myers / Brooker | Myers Construction (USA) | | Alfa Romeo | Giulia Sprint GTA | | Alfa Romeo | TA2.0 |
| 65 | Wintersteen / Starr | Starr Racing (USA) | | Ford | Mustang | | Ford | TA+2.0 |
| 67 | Kleinpeter / Mummery / Hollander | Port of Entry Motors (USA) | Bruce Hollander | Shelby | GT350 | | Ford | GT |
| 68 | Boye / Yuma | Bill Boye (USA) | | Chevrolet | Camaro | I | Chevrolet | TA+2.0 |
| 71 | Chitwood / Barton / Hoffman | Joie Chitwood Thrill Show (USA) | | Chevrolet | Camaro | I | Chevrolet | TA+2.0 |
| 72 | Richards / Adamowicz / Davidson | Davidson Enterprises (USA) | | Porsche | 911 | T | Porsche | TA2.0 |
| 73 | Opert / Grimaldi | Valvoline/Opert Racing (USA) | Fred Opert | Porsche | 911 | | Porsche | TA2.0 |
| 76 | Heppenstall / Lowther / Thompson | Howmet Corp. (USA) | | Howmet | TX | | Continental | P |
| 76T | Heppenstall / Lowther / Thompson | Howmet Corp. (USA) | | Howmet | TX | | Continental | EXP |
| 77 | Stoddard / Drolsom / Gifford / Williams, Jr. | Lewis Wiliams, Jr. (USA) | | Porsche | 911 | | Porsche | TA2.0 |
| 78 | Posey / Kauffman | | | Ford | Mustang | | Ford | TA+2.0 |
| 80 | Rodriguez / Kolb | N.A.R.T.-Harrah Racing (USA) | | Ferrari | Dino 206 S | | Ferrari | P |
| 81 | Piper / Gregory | N.A.R.T.-Harrah Racing (USA) | | Ferrari | 250 LM | | Ferrari | S |
| 96 | Tremblay / Dingman / Gimondo | Vince Gimondo (USA) | | Chevrolet | Corvette | | Chevrolet | GT |