There has never been an in-dash cd player on 164s, only a cd-changer in the trunk with an am/fm/cassette player in the dash and with optional amplifier under the passenger seat. Its easy to fit in most of the chrysler head units (1.5 din) and as you know chrysler units are pretty good and most of the recent ones have mp3 compatibility too.
What I do on all my installs is I get the Chrysler wiring harness and a dash kit from somewhere like Best buy. That way there is no cutting of the wires and the dash is not altered. So if needed you can just plug in the original radio. I have done this to all my cars because the factory radio sucks. Even the Chrysler C/D radios that I have put in sucked as well. The audio controls for both units lack good quality sound. Put yourself a good Pioneer, Alpine, or Kenwood unit in and you will see it is night and day!
Any 1 1/2 din unit should work if that's the look you're going for but most of us here use a standard single din unit with an adaptor plate to fill in the gap. Some have fabbed their own I think my plates were $15.00 and I had a much beter selection of head units to choose from.