Hi Cuba,
Have looked and the only number I could find was 000277. I'm not sure if this is the number for all the Sony Single CD units or just my one. Im sorry I couldn't be of more help.
When you say upgrade are you planning to change the unit or add a CD changer?
At the moment I'm using a 3.5mm jack plugged in,inside the armrest, for my MP3 player which is also Sony. The lead cost £3.99 from Amazon.
Good Luck with your new Kuga.
KC