I own a chain of stereo shops and what I did was have them take the tape deck out and replace it w/ a am/fm/cd/dvd/mp3/satellite head unit.
Put a pull down screen in the ceiling so now have one screen in head unit and one for kids.
Amps, subs and new speakers. Still use old head unit for phone and computer still works.
Tape deck is DIN size.
Good luck.