| 1 | DeLorenzo / Lang | Troy Promotions, Inc. (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+5.0 |
| 2 | Thompson / Mahler | Troy Promotions, Inc. (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 3 | Johnson / Johnson / Greendyke | Doug Bergen Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 4 | Greenwood / Barker | John Greenwood (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 5 | Schumacher / Petree | Wm. A. Schumacher (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 7 | Morehead / Vega | Bruce Morehead Racing (USA) | | AMC | AMX | | Rambler | GT+5.0 |
| 8 | Heinz / Costanzo | Or Costanzo (USA) | | Chevrolet | Corvette | | Chevrolet | GT+5.0 |
| 9 | Grossman / Yenko | Marlbank Racing Team (USA) | Bob Grossman | Chevrolet | Camaro | I | Chevrolet | GT+5.0 |
| 12 | Roethel / Bentley | BRM Inc. (USA) | | Ford | Mustang | Boss 302 | Ford | T5.0 |
| 14 | Siffert / Redman / Kinnunen | J. W. Automotive Engineering Ltd. (GB) | | Porsche | 917 | K | Porsche | S5.0 |
| 15 | Rodriguez / Kinnunen / Siffert | J. W. Automotive Engineering Ltd. (GB) | | Porsche | 917 | K | Porsche | S5.0 |
| 16 | Elford / Ahrens, Jr. | Porsche Audi (USA) | | Porsche | 917 | K | Porsche | S5.0 |
| 17 | Herrmann / Lins | Porsche Audi (USA) | | Porsche | 917 | K | Porsche | S5.0 |
| 18 | Pettey / Hallquist | Paul Pettey (USA) | | Ford | Mustang | | Ford | T5.0 |
| 19 | Andretti / Merzario | Ferrari S.P.A., SEFAC (I) | | Ferrari | 512 S | Spyder | Ferrari | S5.0 |
| 20 | Schetty / Ickx | Ferrari S.P.A., SEFAC (I) | | Ferrari | 512 S | Spyder | Ferrari | S5.0 |
| 21 | Giunti / Vaccarella / Andretti | Ferrari S.P.A., SEFAC (I) | | Ferrari | 512 S | | Ferrari | S5.0 |
| 22 | Parkes / Parsons | N.A.R.T. (USA) | Luigi Chinetti, Jr. | Ferrari | 312 P | Coupe | Ferrari | P3.0 |
| 23 | Adamowicz / Chinetti, Jr. | N.A.R.T. (USA) | Luigi Chinetti, Jr. | Ferrari | 312 P | Coupe | Ferrari | P3.0 |
| 24 | Posey / Bucknum / Everett | N.A.R.T. (USA) | | Ferrari | 512 S | Spyder | Ferrari | S5.0 |
| 25 | Cluxton / Pickett | Harley E. Cluxton, III (USA) | | Ferrari | 365 GTB/4 | /C | Ferrari | GT5.0 |
| 26 | Brown / Young / Ormes | Randy's Auto Body (USA) | Joe Randazzo | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 27 | De Udy / Hailwood | Grand Bahama Racing Car Co. Ltd. (GB) | Mike De Udy | Lola | T70 | Mk.3B GT | Chevrolet | S5.0 |
| 29 | Heppenstall / Grant | Auto Enterprises (USA) | Francis C. Grant | Ford | GT40 | | Ford | S5.0 |
| 30 | Forester / Hedges | Trevor Graham (GB) | | Ford | GT40 | | Ford | S5.0 |
| 31 | Courage / de Adamich | Autodelta S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 32 | Stommelen / Galli | Autodelta S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 33 | Hezemans / Gregory | Autodelta S.P.A. (I) | | Alfa Romeo | T33/3 | | Alfa Romeo | P3.0 |
| 34 | Pescarolo / Servoz-Gavin | Equipe Matra-Elf (F) | | Matra | MS650 | | Matra | P3.0 |
| 35 | Gurney / Cevert | Equipe Matra-Elf (F) | | Matra | MS650 | | Matra | P3.0 |
| 36 | Cuomo / Gimbel / Lisberg | Ray Cuomo Racing (USA) | | Ford | Mustang | | Ford | T5.0 |
| 37 | Collins / Wilson | Collins-Wilson Racing (USA) | | Ford | Mustang | | Ford | T5.0 |
| 38 | Kearney / Chitwood / *Boo / *Floyd / *McClain | David H. McClain (USA) | David H. McClain | Chevrolet | Camaro | I Z28 | Chevrolet | T5.0 |
| 39 | Kemp / Mitchell | Robert B. Mitchell (USA) | | Chevrolet | Camaro | | Chevrolet | T5.0 |
| 40 | Gimondo / Dietrich | Takondo Racing (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 41 | Bock / Dent | Laurel Racing (Larry Drover) (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 43 | Tremblay / McDill | Bruce Behens Racing (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 45 | Attwood / Larrousse / Koch | International Martini Racing Team (D) | Hans-Dieter Dechent | Porsche | 908/02 | K | Porsche | P3.0 |
| 46 | Koch / Larrousse / Attwood / *Dechent | International Martini Racing Team (D) | Hans-Dieter Dechent | Porsche | 908/02 | K Flunder | Porsche | P3.0 |
| 47 | Laine / van Lennep | Racing Team AAW (FIN) | | Porsche | 908/02 | K | Porsche | P3.0 |
| 48 | McQueen / Revson | Solar Productions, Inc. (USA) | | Porsche | 908/02 | K Flunder | Porsche | P3.0 |
| 49 | Greger / Schmalbach | Josef Greger (D) | Sepp Greger | Porsche | 910 | | Porsche | S3.0 |
| 50 | Rahal / Wise / Frank | Nationwide Food Brokers Racing Team (USA) | | Porsche | 906 | | Porsche | S3.0 |
| 51 | Behr / Rosen | Porsche Audi VWNC (USA) | Merwin Rosen | Porsche | 906 | | Porsche | S3.0 |
| 52 | Duval / Bailey / Nicholas | Jacques Duval (CDN) | | Porsche | 911 | T/R | Porsche | GT2.0 |
| 53 | Gregg / Harrison | Brumos Porsche Audi Corp. (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 54 | Arutunoff / Pryor | Automobiles of Italy, Inc. (USA) | | Abarth | 2000 S | SE010 | Abarth | P2.0 |
| 55 | Brennan / Blackburn | British Leyland Motors Inc. (USA) | | MG | B | | BMC | GT2.0 |
| 56 | Woodner / O'Connor | British Leyland Motors Inc. (USA) | | MG | Midget | | BMC | GT2.0 |
| 57 | Belperche / Gammon / Mummery | Waldron Enterprises Inc. (USA) | | MG | B | | BMC | GT2.0 |
| 58 | Scott / Houser / Lanier | Waldron Enterprises Inc. (USA) | | MG | B | | BMC | GT2.0 |
| 59 | Smith / Donley / Buttari | Waldron Motors (USA) | Chris Waldron | MG | Midget | | BMC | P2.0 |
| 60 | Kilpatrick / Goodrich | Herrington Motors (USA) | Bill Herrington | MG | B | | BMC | GT2.0 |
| 61 | Baker / Baker / Richards / Rinzler | Ring Free Oil Racing Team/Baker Motor Co. (USA) | | Chevron | B16 | | Ford | P2.0 |
| 62 | Robinson / Kleinpeter | Chevron Cars (GB) | Brian Robinson | Chevron | B16 | | Ford | P2.0 |
| 63 | Fabre / Aguilar | Carlos Fabre (MEX) | | Chevron | B8 | | BMW | S3.0 |
| 67 | Bandy / Stevenson | Sport Motors (USA) | | Lotus | 47 | | Ford | P2.0 |
| 69 | Spruell / Pickett / *Theodoracopulos | Scuderia Spruell (USA) | | Alfa Romeo | Giulia Spider | | Alfa Romeo | GT2.0 |
| 73 | Guthrie / Smith / Kondratiff / *Seavey | Ring Free Oil Racing Team/Baker Motor Co. (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| 74 | Meaney / Bean | Ralph Meaney, Inc. (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 77 | Jennings / Tullius | Bruce Jennings (USA) | | Porsche | 911 | T | Porsche | GT2.0 |
| 79 | Taylor / Dyer | Del Taylor (USA) | Del Taylor | Alfa Romeo | 1750 GTV | | Alfa Romeo | T2.0 |
| 80 | Kennedy / Tillson / Samm | Texas Speed Museum (USA) | | Lancia | Fulvia | HF | Lancia | T2.0 |
| 81 | Kennedy / Samm / Tillson | Texas Speed Museum (USA) | | Lancia | Fulvia | HF | Lancia | T2.0 |
| 82 | Clark / Marsula | General Plastics (USA) | | Lancia | Fulvia | HF | Lancia | T2.0 |
| 85 | Cooper / Mosher | HCAS, Inc. (USA) | | Opel | Kadett | Rallye | Opel | T2.0 |
| 86 | Polimeni / Theall | Sandy's Spares (USA) | | Volvo | 122 | S | Volvo | T2.0 |
| 87 | Whitaker / Eckoff / Slottag / *Davidson | Robert W. Whitaker (USA) | | Volvo | 122 | S | Volvo | T2.0 |
| 88 | Fleming / Johnson / Bowers | Simone N. Fleming (USA) | | Fiat | 124 | Sport Coupé | Fiat | T2.0 |
| 91 | Corwin / Mims | Flem-Cor Enterprises (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 92 | Gwynne / Elliott | Preston Hood Chevrolet, Inc./John Elliott (USA) | | Chevrolet | Camaro | I | Chevrolet | T5.0 |
| 97 | Brown / Marcus / Sandman | HCAS, Inc. (USA) | | BMW | 2002 | | BMW | T2.0 |
| 99 | Harris / Lewis / LeVasseur | Wm. Harris (USA) | | Austin-Healey | Sprite | | BMC | P2.0 |
| T | Siffert / Redman | J. W. Automotive Engineering Ltd. (GB) | | Porsche | 917 | K | Porsche | S5.0 |