| 2 | Andretti / Ickx | Ferrari Automobili (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 3 | de Adamich / Galli | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 |
| 4 | Regazzoni / Redman | Ferrari Automobili (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 5 | Elford / Marko | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 |
| 6 | Schenken / Peterson | Ferrari Automobili (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 7 | Revson / Stommelen | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/TT/3 | | Alfa Romeo | S3.0 |
| 8 | Fitzgerald / Nehl | Automotive Engineering Enterprises (USA) | | Chevrolet | Camaro | II | Chevrolet | T5.0 |
| 9 | Galli / de Adamich / *Vaccarella / *Hezemans | Autodelta, S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | S3.0 |
| 11 | Thompson / Weaver / DeLorenzo | Ronald R. Weaver (USA) | | Chevrolet | Corvette | C3 Spyder | Chevrolet | GT+2.5 |
| 12 | Wisell / Bonnier / *Larrousse / *Garcia-Veiga | Ecurie Bonnier (CH) | | Lola | T280 | | Ford | S3.0 |
| 14 | Larrousse / Craft / Garcia-Veiga | Ecurie Bonnier (CH) | | Lola | T280 | | Ford | S3.0 |
| 16 | Keyser / Beasley | Toad Hall Racing (USA) | Michael Keyser | Porsche | 911 | ST | Porsche | GT2.5 |
| 17 | Tremblay / Ellis-Brown | C. C. Canada, Inc. (USA) | C. C. Canada | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 18 | Reynolds / Baker / *Grossman | Ring Free Oil Racing Team c/o Baker Motor Co. | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 |
| 19 | McClain / White | David McClain (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 |
| 21 | Chinetti, Jr. / Eaton | North American Racing Team (USA) | Luigi Chinetti, Jr. | Ferrari | 312 P | | Ferrari | S3.0 |
| 22 | Posey / Bucknum / Chinetti, Jr. | North American Racing Team (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 |
| 24 | Buffum / Fitzpatrick | Libra International Racing (USA) | John Buffum | Ford | Escort | I RS 1600 | Ford | T2.5 |
| 25 | Junco / van Beuren, Jr. | Doug Shierson/Fred Opert Mexican-American Racing Team (USA) | Douglas Shierson | Chevron | B19 | | Ford | S2.0 |
| 26 | Craw / Barber | Doug Shierson/Fred Opert Mexican-American Racing Team (USA) | | Chevron | B19 | | Ford | S2.0 |
| 27 | Schuck / Weiss | Dr. Richard Weiss | | Porsche | 911 | S | Porsche | GT2.5 |
| 28 | Kremer / Huber | Porsche Kremer Team (D) | Erwin Kremer | Porsche | 911 | S | Porsche | GT2.5 |
| 32 | Merzario / Soler-Roig | Abarth-Osella (I) | | Abarth | 2000 SP | SE021 | Abarth | S2.0 |
| 33 | Stafford / Stafford | R. Sheldon Stafford (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 39 | Brezinka / Bartling / Pechmann | R. Brezinka (CDN) | | Porsche | 910 | | Porsche | S3.0 |
| 40 | Pentecost / Torgersen | Northlake Porsche Audi Inc. | Levon Pentecost | Porsche | 911 | S | Porsche | GT2.5 |
| 41 | Kirill / Norburn | Kirill Racing/Brundick Motor Co. Ltd. (USA) | Peter Kirill | Porsche | 911 | S | Porsche | GT2.5 |
| 42 | Sereix / Noseda / *Cao | Jose Garcia b/d/ a Garcia Racing (USA) | Jose Garcia | Chevrolet | Camaro | II | Chevrolet | T5.0 |
| 43 | Garcia / Garcia / *Garcia | Garcia Racing (USA) | | Chevrolet | Camaro | II | Chevrolet | T5.0 |
| 47 | Gimondo / Dietrich | Takondo Racing (USA) | Vincenzo Gimondo | Chevrolet | Camaro | II | Chevrolet | T5.0 |
| 48 | Adamowicz / Greenwood | John Greenwood Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 50 | Yenko / Cordts | John Greenwood Racing (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 |
| 51 | Spirgel / Mollin | Warren Shiber | | Chevrolet | Corvette Sting Ray | C2 | Chevrolet | GT+2.5 |
| 52 | Chitwood / Chitwood | Chitwood Chevrolet, Inc. (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 53 | Oleyar / Luebbe | Michael Oleyar (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 54 | Goellnicht / Pryor | Automobile International Inc. (USA) | Brian Goellnicht | Abarth | 2000 S | SE010 | Abarth | S2.0 |
| 55 | McCaig / McCaig | Roger McCaig Racing (CDN) | | Lola | T212 | | Ford | S2.0 |
| 56 | Waugh / Kleinpeter | Promotional Advertising Corp. (USA) | Hugh Kleinpeter | Lola | T212 | | Ford | S2.0 |
| 57 | Johnson / Heinz | Dave Heinz Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 58 | Rebaque / Rojas | Brumos Porsche Audi Corp. | | Porsche | 914 | /6 | Porsche | GT2.5 |
| 59 | Haywood / Gregg | Brumos Porsche Audi Corp. (USA) | | Porsche | 911 | S | Porsche | GT2.5 |
| 60 | Fordyce / Small | Robert Fordyce | | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 61 | Locke / Bailey | James Locke (USA) | James Locke | Porsche | 911 | S | Porsche | GT2.5 |
| 62 | de Bagration / Fernandez | Escuderia Montjuich | | Porsche | 908/03 | | Porsche | S3.0 |
| 66 | Belperche / Rollin | John Belperche | | Porsche | 911 | S | Porsche | GT2.5 |
| 70 | Harrington / Bock | Gene Harrington (USA) | Gene Harrington | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 72 | McDonald / Everett | Lee McDonald, Algar Porsche Audi (USA) | | Porsche | 914 | /6 | Porsche | GT2.5 |
| 74 | Straub / Mosher | Norman Mosher | | Ford | Mustang | | Ford | T5.0 |
| 75 | Clark / Kearney | Clearwater Datsun | Don Kearney | Datsun | 510 | | Datsun | GT2.5 |
| 76 | Stone / Jennings | Silverstone Racing Team (USA) | George Stone | Porsche | 911 | ST | Porsche | GT2.5 |
| 79 | Johnson / Young | Arrow Racing Team (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 80 | Elliott / Gwynne | Preston Hood Chevrolet, Inc. (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 81 | Muniz / Novoa / *Izquierdo | Daniel Muniz (MEX) | | Porsche | 914 | /6 | Porsche | GT2.5 |
| 82 | Dean / Brown | A. G. Dean (GB) | | Porsche | 908/02 | K | Porsche | S3.0 |
| 86 | Fleming / Boggs | Simone Fleming (USA) | | Pontiac | Firebird | | Pontiac | T5.0 |
| 87 | Baker / Baker | Buck Baker | | Pontiac | Firebird | | Pontiac | T5.0 |
| 88 | Kemp / Fraser / Smith | Smith-Kemp AutoRacing Team | Bobby Rinzler | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 89 | Gafford / Smith / Fraser | Smith-Kemp AutoRacing Team | Bobby Rinzler | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 93 | Houser / Shaw, Jr. / *Yates | Bolus & Snopes, Ltd. | | Shelby | GT350 | | Ford | T5.0 |
| 94 | Mitchell / Christiansen | Bolus & Snopes, Ltd. (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 99 | Whitaker / Currin | Phil Currin (USA) | | Chevrolet | Corvette | C2 | Chevrolet | GT+2.5 |