clk w209 upgrade too sat nav

[johnunleashed]

Hello to all , I have just bought a 2009 clk 280 for my wife , Its has the std cd player with the disc changer in the glove box , Im looking to upgrade . I have found a head unit and Arial on line for sale , Is it just a matter of removing the old head unit and plunging the sat nav in , or do I need new leads etc , many thanks for your help in this matter