Radio GL1500 retrofitting an AUX input. It can be any audio source can be fed. The AUX input is galvanically decoupled via separator. This eliminates interference (alternator) are effectively suppressed and the radio electronics is protected against external voltages and transients. The switch to AUX is done by switch to cassette with an empty cartridge slot. For retrofitting the radio must be removed and sent to me in the workshop. Or simply come up with the Wing over.