you got me thinking about how cool it would be to find an old formula 1 broadcast from watkins glen or the like... i did a little bit of searching and only came up with this:
http://www.myoldradio.com/old-radio-episodes/auto-racing-first-30-minutes-of-the-indy-500Its the beginning of the 1949 Indy 500... enjoy. if you come across anything be sure to post back.