Chrysler was the official vehicle sponsor for the show and there were some really neat one-offs used - like the 1972 Challenger convertible (Yes 1972, a year after Chrysler stopped making convertibles). They also supplied the one and only 1972 Barracuda ragtop for the Brady Bunch - remember the episode where Bobby shoves the umbrella throught the convertible top at the drive-in when Greg had to drag him along on his date? That was the '72 blue Barracuda ragtop.
Anyway, I dont recall any Corvettes used on the show. I used to watch it as a kid just to see the Mopars. (My grandfather was an exec at ABC at the time and used to get us all kinds of promotional items from all the shows. We still have a lot of it somewhere in the family archives
)