Although the L78, L89, and COPO options weren't advertised. It was common knowledge that they were available. The L78 and L89 could be checked off on the order sheet. The COPO was buried a little deeper, but still available to anyone who knew that it was there. I think that the Z16 was strictly a promotional deal and the cars were handed out to people like Dan Blocker for their use. Eventually the cars trickled down to the street people after the celebrities were done with them. GM didn't want to stir up the government and safety people any more than they already had. GM even banned official racing in '63. It looked pretty good when a little guy like Jenkins beat the factory backed Fords and Chryslers. In actual fact Grumpy and others were being looked after through the back door. It was all pretty slick.
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Chevelleless after 46 years......but we did find a low mileage, six speed, silver 2005 Corvette. It will just have to do for now.