Did you know that the earliest ZR1 Corvettes came into existence long before any of these later iterations? If not, then take a few minutes to acquaint yourself with one the rarest small-block production Corvettes of all time - the 1970-1972 Corvette ZR1. From 1970 to 1972, Chevrolet offered the ZR1 Special Engine Package, which featured a small-block LT1 engine.