Interesting to watch this bit of aerospace history. As a recent engineering graduate, I was a member of LMSC launch operations from 1959 to 1969. We launched Agena’s on Thors, Atlas, and Titan boosters. I still have my 100th Agena launch pin. It was a great time.
It's a pity the Agena-2000 was never developed and put into production otherwise we'd have seen the return of the Atlas-Agena with the Atlas V as the first-stage.