Down the YouTube rat-hole you sent me to I found this little clip of the 1973 Laguna Seca Can-Am. I was in the grandstands at that race right behind the cameraman's point-of-view. I still have a few Kodachromes of Donohue working his way from last to first, passing Follmer's Rinzler 917/10 for the lead in what was then Nine. Seems like yesterday...
YouTube - Can-Am Race Laguna Seca 1973