What 1978 race did the Corvette pace for the first time?

The Corvette paced the Indianapolis 500 for the first time in 1978.

The 1978 race marked the Corvette’s debut as an Indianapolis 500 pace car. A C3 Corvette led the field for the 62nd running of the race at Indianapolis Motor Speedway on May 28, 1978, with former Indy 500 winner Jim Rathmann driving the pace car.

The appearance coincided with the Corvette’s 25th anniversary and made the 1978 model year especially notable. Chevrolet produced 6,502 black-and-silver Indy 500 pace-car replicas, equipped with distinctive styling and special interior features. The same year also brought the fastback rear window and Silver Anniversary edition.

This question concerns pace-car duty, not Corvette participation in endurance racing. Sebring and Le Mans are separate events, while Daytona 500 is a stock-car race. The Corvette returned to Indy pace-car duty several times, including 1986, 1995, 1998, and 2002, but 1978 was the first.