I have an old 3gs phone with a ringtone I want, I now have a 5s - read the whole question before responding!

I have an old 3gs phone with a ringtone I want. I now have a 5s.

Before I got the 5s, I lost the disk that contained my itunes.. I had a much older version saved on another disk - so I got most things back, but there is a ring tone on the 3gs that I would really like on my 5s. When I start to sync the 3gs with itunes now - when I click to sync the tones, it asks if I want to replace everything on the 3gs with what is currently in itunes (which doesn't have this particular tone - because I got it after that backup was made).. .if I say yes, I will lose that tone.

Is there anything I can do? I can see old backup's of the 3gs phone, but when I started to do a restore, it didn't let me choose the backup to use.

Any ideas on how to get this tone off the 3gs onto the 5s?

Thank you!