wire diagram

Hello everyone. Im new to the forum and need a little help. I have a 99BMW 528i and are looking to do a stereo upgrade. I want to change the head unit and change the interior speakers. Does anyone on the forum have or can scan the wiring diagram for this car. I would really aprieciate it. By the way will I need a dash kit for a single din or double . unit. Where can I buy this and a aftermarket wire harness. If possible please post links.