Getting a head unit

This may have been posted somewhere here before but I don't follow this thread a whole lot. Can anyone tell me where to get a aftermarket head unit or the things I need to replace the base model unit. Thanks, Jay

http://www.mustang6g.com/forums/showthread.php?t=15692

http://www.mustang6g.com/forums/showthread.php?t=42152&page=7

http://www.mustang6g.com/forums/showthread.php?t=38767&page=41

http://www.mustang6g.com/forums/showthread.php?t=40813&page=15