Axe, Seb showed up at all the USAC races. I believe the car was #45, but I could be wrong about that. I know Duke drove it and I remember Vogler being in the car and having some serious steering issues. I believe that might even be talked about in the Vogler book. He bought the second car he ran in USAC off of Ray Smith.
Come to think about it, Seb, might have started USAC in the late 60's. Duke would know for sure.