Well, I know you can get a cord that will plug into the headphone jack of the master device, and into the mic jack of the digital recording device (Radio Shack or Micro Center should have one) and you can record just like speaking into a microphone on your computer or other digital recording device. From there you can convert to whatever sound file you'd like.

As for what's going to last 43 years, I have zero clue. You might call someone at, say, Emerson, where they have a good sound engineering department and pose the question there.