Few automobiles occupy a more fascinating corner of Corvette history than the five original 1963 Chevrolet Corvette Grand Sports.

They weren't production Corvettes with bigger engines. They weren't ordinary Sting Rays converted into race cars. And despite their familiar C2 silhouette, they shared surprisingly little with the Corvette sitting on a Chevrolet showroom floor in 1963.

Few cars invite closer inspection than a 1963-1967 Chevrolet Corvette. At any show, auction, or cars-and-coffee, someone will eventually lean over the passenger-side fender looking for numbers. There's a good reason: the difference between an ordinary small-block Sting Ray and a documented, original-drivetrain big-block car can be six figures or more.

This guide shows you how to read those numbers, what each one can prove, and where each one stops.