True, the unit code[PAL] is in the sirius reciever and the interface box is the same so it should be a plug and play. Shouln't even have to re-subscribe. FYI the Ford radio is actually a Clarion unit that Ford bought thru Delphi.
I have an Eclipse AVN5510 in my Tundra, and I am very happy with it. However, I do think that the sirius interface that comes from the factory will only mate up to a factory headunit. I am not sure, though. The sirius subscription is permanently attached to the OEM interface.If you have went that far, I would put in a new head unit W/Nav before I would reinstall another Shaker. Eclipse makes a good one. AVN 5500 or 6600. It also has Ipod, Sirus, Blutooth, TV, CD & DVD. Your Subscription to Sirus should carry with you no matter what you have in the car.