Audio Systems: 2001 Buick Century, buick century aux input

Question
I have a 2001 Buick Century with Concert Sound.  It appears to have an early version of On-Star, 9 speakers.  AM/FM CD.  I will be giving this vehicle to my college aged student but want them to be able to access IPOD/MP3 players.  Do I need a new head unit containing USB, AUX input, and/or IPOD input?  Can these be added to the rear of the OEM deck with connection wires available from behind the dash?  The existing speakers and system sound fine.  Will the OEM speakers be able to handle an aftermarket deck?

Answer
Most of Buck Century come with a 10 pin plug in the trunk for the external cd changer
if that is the case you can add the GM10-AUX and input audio
http://www.oemautosound.com/pc-507-81-pie-gm10-aux-buick-1995-2001-auxiliary-inp

if the vehicle is not prewire you can still add the interface,but it will be done behind the radio and you have to connect 9 wires one by one, the other option is the
USB interface works for USB iPod iPhone and Sirius Satellite radio
rds iPod USB interface


or the Bluetooth android interface
android interface


if you replace the radio, its a good idea to replace all the speakers
good luck