Regret I cannot help with part numbers. However, being less technical, I wonder if it would be easier to buy a satnav with bluetooth that you can take to your next car? Garmin do a few which will sync with most modern phones.
I doubt your efforts would realise any significant benefit on trade-in, so seems a lot of effort for little return.
All the best if you do decide to tackle it!
2008 model 1.8 petrol C-Max Zetec in Avalon Blue - arrived 14 May 2011. Also own and drive: 2005 Mercedes Benz SLK350 and wife\'s Fiat Panda 1.2 skydome.