| 1 | Hobbs / Scott | Kirk F. White Motor Racing Inc. (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 | |
| 2 | Andretti / Ickx | Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 | |
| 3 | Peterson / Schenken | Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 | |
| 4 | Regazzoni / Redman | Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 | |
| 7 | Bell / van Lennep | Gulf Research Racing Company (GB) | | Mirage | M6 | | Ford | S3.0 | |
| 8 | Nehl / Fitzgerald | Automotive Engineering Enterprises (USA) | | Chevrolet | Camaro | II | Chevrolet | T5.0 | Sedan A |
| 9 | Summers / McClure | Endurance Promotions, Inc. (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 10 | Tremblay / Ellis-Brown | C. C. Canada Lumber Co., Inc. (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 11 | DeLorenzo / Thompson | Troy Promotions, Inc. (USA) | | Ford | Mustang | | Ford | T5.0 | Sedan A |
| 12 | Larrousse / Bonnier / Wisell | Ecurie Bonnier (CH) | | Lola | T280 | | Ford | S3.0 | |
| 15 | Bean / Pentecost / *Torgersen | Toad Hall Racing (USA) | | Porsche | 911 | S | Porsche | GT2.5 | |
| 16 | Keyser / Barth | Toad Hall Racing (USA) | Michael Keyser | Porsche | 911 | ST | Porsche | GT2.5 | |
| 17 | Gimondo / Dingman | Takondo Racing (USA) | | Chevrolet | Camaro | II | Chevrolet | T5.0 | Sedan A |
| 18 | Ingle / Reynolds | Ring Free Oil Racing Team (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 | |
| 19 | McClain / White | David H. McClain (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 21 | Adamowicz / Posey | N.A.R.T. (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 | |
| 22 | Chinetti, Jr. / Grossman | N.A.R.T. (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 | |
| 23 | Kemp / Koveleski | Rinzler Motoracing, Inc./Holiday Anns of America (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 | |
| 24 | Buffum / Fitzpatrick | Libra International Racing (USA) | John Buffum | Ford | Escort | I RS 1600 | Ford | T2.5 | TU |
| 25 | Craw / Barber | Fred Opert (USA) | | Chevron | B19 | | Ford | S2.0 | |
| 26 | Junco / van Beuren, Jr. | Fred Opert (USA) | | Chevron | B19 | | Ford | S2.0 | |
| 27 | Kirby / Hotchkis / *Cuddy | Bozzani Porsche Audi, Inc. (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 28 | Kremer / Huber / Bolanos | Porsche Kremer Racing Team (D) | Erwin Kremer | Porsche | 911 | S | Porsche | GT2.5 | |
| 29 | Schumacher / Kiefer | Iroquois Racing Associates (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 | |
| 30 | Quintana / Belperche | Florida Tire Co., Inc. (USA) | | Shelby | GT350 | | Ford | GT+2.5 | |
| 31 | Stommelen / Revson / de Adamich | Autodelta, S.p.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 | |
| 32 | Elford / Marko | Autodelta, S.p.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 | |
| 32T | | Autodelta, S.p.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | S3.0 | |
| 33 | Vaccarella / Hezemans | Autodelta, S.p.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 | |
| 34 | de Adamich / Galli / *Hezemans / *Vaccarella | Autodelta, S.p.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 | |
| 35 | Collins / Gonzalez / Beall | Dr. V. P. Collins (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 37 | Belcher / Stevens | Gary Belcher (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 38 | Fisher / Ponder | Hobby Car Enterprises (USA) | Robert Fisher | Chevron | B16 | | Ford | S2.0 | |
| 39 | Pechmann / Bartling / Minter | R. Brezinka (CDN) | | Porsche | 910 | | Porsche | S3.0 | |
| 41 | Kirill / Norburn | Kirill Racing (USA) | Peter Kirill | Porsche | 911 | S | Porsche | GT2.5 | |
| 42 | Noseda / Garcia / Livingston | Garcia Racing (USA) | Jose Garcia | Chevrolet | Camaro | II | Chevrolet | T5.0 | Sedan A |
| 43 | Sereix / Garcia | Garcia Racing (USA) | | Chevrolet | Camaro | II | Chevrolet | T5.0 | Sedan A |
| 44 | Garcia / Cao | Larrauri Racing (USA) | | Chevrolet | Nova | | Chevrolet | T5.0 | Sedan A |
| 45 | West / Tunstall | T. C. Racing (USA) | John Tunstall | Shelby | GT350 | | Ford | GT+2.5 | |
| 46 | Potter / Ansley / Hood | Sebring Racing Inc. (USA) | | Ford | Mustang | | Ford | T5.0 | Sedan A |
| 47 | Gray / Keller | Sebring Racing Inc. (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 | |
| 48 | Greenwood / Smothers | John Greenwood Racing (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 | |
| 50 | Yenko / Cordts | John Greenwood Racing (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 | |
| 51 | Crebs / Jobe | Richard E. Crebs (USA) | | Alfa Romeo | 2000 GTV | | Alfa Romeo | T2.5 | Sedan B |
| 52 | Kleinpeter / Belcher | Promotional Advertising Corp. (USA) | | Chevron | B21 | | Ford | S2.0 | |
| 53 | Baumgartner / Herman / Andrews | D. A. Baumgartner Jr. (USA) | | Chevron | B8 | | BMW | S2.0 | |
| 54 | Arutunoff / Goellnicht | Automobiles International, Inc. (USA) | | Abarth | 2000 S | SE010 | Abarth | S2.0 | |
| 55 | McCaig / McCaig | Roger McCaig Racing (CDN) | | Lola | T212 | | Ford | S2.0 | |
| 56 | Waugh / Beatty | Promotional Advertising Corp. (USA) | Hugh Kleinpeter | Lola | T212 | | Ford | S2.0 | |
| 57 | Heinz / Johnson | Dana English (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 | |
| 58 | Rebaque / Rojas | Brumos Porsche Audi Corp. (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 59 | Gregg / Haywood | Brumos Porsche Audi Corp. (USA) | | Porsche | 911 | S | Porsche | GT2.5 | |
| 60 | Fordyce / Small | Robert Fordyce (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 61 | Locke / Bailey | James N. Locke (USA) | James Locke | Porsche | 911 | S | Porsche | GT2.5 | |
| 63 | Greger / Blank / *Hild | Josef Greger (D) | | Porsche | 910 | Spyder | Porsche | S2.0 | |
| 64 | Baechle / Burdick | Central New York Endurance Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 | |
| 67 | Armstrong / Bremner | Frossman Racing Service (CDN) | | Mazda | R100 | | Mazda | T2.5 | TU |
| 68 | Stoddard / Hines, Jr. / Harmstad | H&S Imports Racing (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 69 | Oest / Tillson / Holbert | Holbert's Porsche-Audi Inc. (USA) | | Porsche | 911 | T | Porsche | GT2.5 | |
| 70 | McDonald / Everett | Lee McDonald-Algar Porsche Audi, Inc. (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 73 | Ross / Groleau | Ross Racing Ltd. (USA) | | Datsun | 240Z | | Datsun | GT2.5 | |
| 74 | Rosen / Schaub | Carousel Porsche Audi, Inc. (USA) | Merwin Rosen | Porsche | 906 | | Porsche | S2.0 | |
| 75 | Clark / Kessler | Clearwater Datsun (USA) | | Datsun | 510 | | Datsun | T2.5 | Sedan B |
| 76 | Stone / Poole | Silverstone Racing Team (USA) | George Stone | Porsche | 911 | ST | Porsche | GT2.5 | |
| 77 | Jennings / Beasley | Bruce Jennings (USA) | Bruce Jennings | Porsche | 911 | S | Porsche | GT2.5 | |
| 78 | Muniz / Luis / Novoa | Daniel Muniz (MEX) | | Porsche | 914 | /6 | Porsche | GT2.5 | |
| 79 | Johnson / Young | Arrow Racing Team (USA) | | Chevrolet | Camaro | | Chevrolet | GT+2.5 | |
| 80 | Elliott / McDill | Preston Hood Chevrolet Inc. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 | Sedan A |
| 84 | Montalvo / Pauley | Chem Air Spray Inc. (USA) | | BMW | 2002 | | BMW | T2.5 | Sedan B |
| 89 | Smith / Gafford | Rinzler Motoracing, Inc. (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 | Sedan A |
| 94 | Mitchell / Christiansen | Bolus & Snopes, Ltd. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 | Sedan A |
| 97 | Quintanilla / Martinez | Robeto Quintanilla Jr. (MEX) | | Chevrolet | Camaro | I | Chevrolet | T5.0 | Sedan A |
| | Autodelta | | Alfa Romeo | T33/3 | | Alfa Romeo | S3.0 | |