That's the Blue #56 - the first person to contact bar none is John Mahoney - he will have it - I looked up the year in A Dirt Road to a Silver Crown and in the USAC 50th Anniversary books and John has shots but probably not exactly what you need. . Brad Dickison and I announced several of those races including the finale at Las Vegas (quite a tale) - Jeff Kristensen of Raceway Video (in LA in think) I believe taped that finale (I have a race tape he did from there and I think it is it) so you might try him as well. There was also a real energetic and funny African American photog who I think was named Tyler (someone can help me here) who tended to show up at PIR, Sacramento etc.