It was a legend.  Corvettes originally equipped with it sell for multiple six figures.  There were only two.
   
The “ZL-1.”
   
Available only in the 1969 model year, the ZL-1 was an all aluminum 427 designed for racing.  In addition to the two Corvettes, there were sixty-nine Camaros equipped with the motor.  It was phenomenally expensive, but the purported power output of 430 hp was substantially understated.  As delivered, the engine produced well over 500 hp.  Though only available in the one model year, the supply of ZL-1s is somewhat greater, because GM continued to make the engine available over the parts counter for several years after that, mostly to support race teams.
   
General Motors’ Performance Division is now releasing a crate motor version of the ZL-1 called the “Anniversary 427.”  It is built from the original ZL-1 tooling, with minor updates. It comes with a 4 bbl carburetor, forged crank, aluminum heads, aluminum block, forged steel rods, roller cam, aluminum dual-plane intake manifold, a two  year, 24,000 mile warranty, and a certificate of authenticity.  A cast-iron block version is also available.

The Anniversary 427 production is limited to 427 engines and they don’t become available until early 2008.

Be a good idea to place the order now, if you want one.