| 10 | Bell / Pace | Gulf Racing Research Co. (GB) | | Mirage | M6 | | Ford | S3.0 |
| 11 | Jordan / Crean | John Crean Racing (USA) | | Chevron | B21 | | Ford | S2.0 |
| 16 | Keyser / Beasley | Toad Hall Racing (USA) | Michael Keyser | Porsche | 911 | ST | Porsche | GT2.5 |
| 17 | Schumacher / Nagel / Lowther | Bill Schumacher (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 18 | DeLorenzo / Reynolds | Baker Motor Co. - Castrol Oil Racing Team (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 |
| 20 | van Lennep / Adamowicz | Gulf Racing Research Co. (GB) | | Mirage | M6 | | Ford | S3.0 |
| 21 | Posey / Hobbs | North American Racing Team (USA) | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 |
| 22 | Jarier / Young | North American Racing Team | | Ferrari | 365 GTB/4 | | Ferrari | GT+2.5 |
| 23 | Pickett / Kemp | Rinzler Motor Racing - Holliday Inns, Inc. (USA) | Bobby Rinzler | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 24 | Cluxton / Moran | North American Racing Team | | Ferrari | Dino 246 GT | | Ferrari | GT2.5 |
| 25 | Schuster / Perez Gama | Marathon - Douglas Shierson Racing (USA) | | Chevron | B19 | | Ford | S2.0 |
| 26 | Shierson / Barber | Marathon - Douglas Shierson Racing (USA) | Douglas Shierson | Chevron | B19 | | Ford | S2.0 |
| 27 | Mollin / Weiss | Richard C. Weiss | | Porsche | 911 | S | Porsche | GT2.5 |
| 28 | De Cadenet / Birrane | Alain de Cadenet (GB) | | Duckhams | LM | | Ford | S3.0 |
| 29 | van Beuren, Jr. / Buffum | Libre International Racing | John Buffum | Chevron | B21 | | Ford | S2.0 |
| 31 | Alden / Wiernicki / Wiernicki | Neil Allen | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 33 | Minter / Patrick | Otto Zipper Racing Team (USA) | | Alfa Romeo | T33/3 | | Alfa Romeo | S3.0 |
| 35 | Kepler / Orr | Velvetouch GT | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 36 | Miller / Orr / Miller / Kepler | Velvetouch GT | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 37 | Sherman / Lo Bianco | LoBianco Trucking, Inc. (USA) | Pete Lo Bianco | Chevron | B19 | | Ford | S2.0 |
| 39 | Bartling / Petermann / Brezinka | Ray Brezinka (CDN) | | Porsche | 910 | | Porsche | S2.0 |
| 42 | Jöst / Casoni | Reinhold Joest (D) | Reinhold Jöst | Porsche | 908/03 | | Porsche | S3.0 |
| 43 | O'Steen / Helmick / *Kremer | Ecurie Escargot (USA) | Dave Helmick | Porsche | 911 | S | Porsche | GT2.5 |
| 48 | Greenwood / Smothers / Cordts | John Greenwood Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 49 | Greenwood / Smothers / *Cordts / *Long / *Greendyke | John Greenwood Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 50 | Greenwood / Long | John Greenwood Racing (USA) | | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 |
| 52 | Kleinpeter / Belcher | Promotional Advertising Corp. | | Chevron | B21 | | Ford | S2.0 |
| 55 | McCaig / McCaig | Roger McCaig Racing (CDN) | | Lola | T212 | | Ford | S2.0 |
| 57 | Heinz / Johnson | Race Enterprises and Development, Inc. (USA) | Dana English | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 59 | Haywood / Gregg | Brumos Porsche-Audi Corp. (USA) | | Porsche | 911 | S | Porsche | GT2.5 |
| 61 | Locke / Bailey | Jim Locke (USA) | James Locke | Porsche | 911 | S | Porsche | GT2.5 |
| 63 | Oleyar / Luebbe | Michael Oleyar (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 64 | Baechle / Laughlin | C. Weaver Chevrolet (USA) | Ronald Weaver | Chevrolet | Corvette | C3 | Chevrolet | GT+2.5 |
| 66 | Murray / Knupp | Mike Murray (USA) | | Chevrolet | Corvette | | Chevrolet | GT+2.5 |
| 68 | Dean / Brown | A. G. Dean (GB) | | Porsche | 908/02 | K | Porsche | S3.0 |
| 77 | Stone / Jennings | Silverstone Racing (USA) | George Stone | Porsche | 911 | T | Porsche | GT2.5 |
| 80 | Hochreuter / *Bytzek | Kennedy-Car Collision (CDN) | | Porsche | 911 | | Porsche | GT2.5 |
| 85 | Andretti / Ickx | SEFAC Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 86 | Peterson / Schenken | SEFAC Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 87 | Redman / Merzario | SEFAC Ferrari (I) | | Ferrari | 312 PB | | Ferrari | S3.0 |
| 88 | Abate / Soltau | Edwin Abate, D.D.S. (USA) | | Porsche | 910 | | Porsche | S2.0 |
| 89 | Oest / Tillson | Holbert's Porsche-Audi (USA) | | Porsche | 911 | T | Porsche | GT2.5 |
| 90 | Wisell / Larrousse | Ecurie Bonnier (CH) | | Lola | T280 | | Ford | S3.0 |
| 93 | Fisher / Gloy | Hobby Car Enterprises | Bobby Fisher | Chevron | B16 | | Ford | S2.0 |
| 99 | Wechsler / Heppenstall | Robert Wechsler | | Royale | RP4 | | Ford | S2.0 |