I believe the first year (1974) they used 1973 Porsche Carrera RSR's, the second year (1975) they used 1974 Camaros.
Here's a great photo. How would like to see this group in your rear view mirror?
From 1979 : Mario Andretti, Cale Yarborough, Bobby Allison, Alan Jones (F1 Champion), Tom Sneva, and Neil Bonnett.
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My Bio: I am currently writing articles for POCI's Smoke Signals magazine and enjoy promoting and discussing the history of the Pontiac Motor Division.