Hello All, Would you believe Shelby marketed cam shafts for Chevys? They did... Out of the AutoSport Products Incorporated, High Performance Parts Division, catalog dated to 1969: Called the Mark IV Road and Drag, sm blk #GCWD-6250-E, big blk #GCPD-6250-H Mark VIII Super Road and Drag, sm & big blk #GCWD-6250-A & #GCPD-6250-C Something to torment your GM buddies with. Have fun. cheers ~Earl