if your talking about an input for a discman or similar, your best bet is the eurovox tape deck from any commodoore of around the VN to VS range (not sure when they stopped putting those models in them). you should be able to pick up one cheap from your local wrecker or from some fully sik commy driver that has just replaced his.
i've got one but there is something wrong with it ( yet to be determined ) so that is probably not much good to you.
hope that helps.