I fished around on the Sirius and XM sites and the Ford site for my 2007. No longer available. I did find that there are receivers, connection modules, cables and antennae available from a site on the web.
I estimated the cost to be around $200 for all the bits and pieces, plus the monthly sub fee. If I were to get the service, I would get a mobile receiver that could be plugged into the home stereo so I could use the service whether at home or in the car.
There was one model that plugged into the 'power outlet', aka cigar lighter, and broadcast its satellite signal on an unused FM frequency, and, I think, had the options of using L/R RCA phono type inputs if the stereo had them available.