What size are the front and rear speakers in a 1977 Chevy Nova?

There's no single answer to the size of the front and rear speakers in a 1977 Chevy Nova. The factory didn't specify a single speaker size, and many owners customized their sound systems over the years. The size varied depending on whether the car had a factory radio and what aftermarket upgrades, if any, were installed. You'd need to physically inspect the speaker locations in the specific 1977 Nova to determine the size.