Like I said before, the best, most accurate way is to get them race weekend at the track or online. As for the PL, DCS etc, those you will probably only get by buying a list at the track, as I said they can change weekly. Teams may use different frequencies and tones at each track because of intereference from other users. Indy is one of the more difficult areas due to the number of radios used at the track alone, not too mention all the businesses around the track and nearby. Most online sources do not have the tones, the ones you pay for ($5) at the track may or may not have the tones. I always get them from someone at the track so I don't worry about it much, and I don't bother getting them until race morning, but then I get there at 4am and have lots of time to kill before the race starts
V