As Fl@pper says, the older cars have two 3.5mm headphone jacks in the back. I learnt about it from this forum. nothing in the manual about it really.
Plug your headphones in and press turn the stereo to the function you want i.e. tape, cd, radio and press phone (the sound will come out through the headphones) and adjust the volume to the required level. Now here's the cool part. When someone in the back is listening to the Famous Five story, you can then listen to another source. So if they're listening to a tape, you can listen to a CD or the radio. Have a play around with it. Its great if your on a long journey with kids. cheaper than a portable dvd player.