There will be a connection on the rear of the head unit, this is a 2/3 row 8 pin plug. - I can't remember exactly, but i will go and have a look later, but its very cold outside.
The CD changer you need or which is recommended by Fiat is the Philips RC 026 (or the VDO 026 (which is the newer replacement)). If you purchase one off eBay make sure it has the red adapter as they can also be used in the Bravo/a which uses a different plug (3,2,3) if i recall and this changes the plug.
One thing i will say about the CD changer is they tend to skip alot as the Punto's ride was never smooth. If you have an ipod i would recommend the adapter that fits into the same socket on the rear of the headunit.
But the quality is superb even through the existing speakers, and it works with the steering wheel controls also (Tune - next track, Band - change CD, Vol Up and Vol Down - Volume).
Links:
- This link contains the plug you don't want (unless you find the adapter on eBay too);
http://cgi.ebay.co.uk/Philips-RC-02...oryZ3289QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
- This one contains the adapter you need in order to convert the connection;
http://cgi.ebay.co.uk/Philips-RC-02...oryZ3289QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
- And another similar one - which says it includes the adapter;
http://cgi.ebay.co.uk/Philips-Car-C...oryZ3289QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
This is a pic of the CD changer when i took it out to clean:
Hope this helps,
Matt