Actually the dual snorkle design air cleaners were used as early as Jan or Feb on LS6 Chevelles. There was a car on Ebay awhile back (white w/ blk stripes I think) that had a buildsheet showing "CO" and a build date of Jan or Feb. I thought I had saved a pic of the buildsheet, but can't seem to find it. The car if I'm not mistaken was a Baltimore car.