Greg,
I was in the Special Order Group (COPO) at Chevy, from 1968 thru 1971. Most of the pilot builds also came through our department. The time line for the build date of your LS6 Chevelle sounds like it "could" have been a pilot car. If you can give me some more information (possibly off-line), I'll do my best to help!
Jim Mattison
[email protected]