If your not confident in cutting the wires to your existing radio, and not everyone is, then if you take existing radio to a half decent radio supplier when you buy the new radio they can probably identify what changeover plug you will need, it's then simply plug a short lead with a plug at each end, one end go's to the supply in caravan that powered your old radio and the other end either straight in the back of the new radio or into the plug that comes with your new radio, wiring a radio is really really easy but not everyone will have the tools or the ability/confidence to doit themselves, the changeover plugs are available for loads of radios so always an option. BP