Pull the boot carpet lining away from the passenger side wheel arch, if you find a wiring loom underneath then this will most probably be the changer connection, if its taped well to the underside of the lining then the car just didn't have the changer as an extra from factory, but if its lose then it probably had one but has been removed. Changer around 30 notes on flee bay. As for front just do the same but with passenger foot well carpet or behind glove box, I think the loom has 4 pretty coloured wires with a blue connector.