Hi for what its worth I have a 2005 4200 CC and the NavTrak unit is located under the rear parcel shelf. I had a new one installed some years after buying the car, I seem to remember access through the rear seat central armrest, just pull the leather inset down from the top to reveal some heavy metal framework, but can not remember any further details. I have not bothered renewing for years and would like to take mine out completely if any body has an idiots guide, this idiot would be grateful as he is getting fed up with the constant battery drain. Cheers