I would do yourself a favor and just buy an aftermarket headunit. Blaupunkts have a tenancy to constantly crap out after a while. My sister went through 4 in the life time of her owning the car and they were all replaced free of charge by the dealer.
2003 Ford Focus ZX3("FUBARCUS" was "Brokus") - old and still busted
2007 Subaru Impreza 2.5i - current DD