Don Yenko found three different ways around GM’s rule capping Camaro engines at 400 cubic inches, hand-swapping in 427s for 1967 and 1968 before finally getting Chevrolet to build the combination on the factory line for 1969. With production numbers as low as 54 cars in the first year, these remain some of the rarest true muscle cars ever built. Read on for the year-by-year breakdown of exactly how each version came together.