I travel to Canada a lot and I always have international roaming for using my GPS on my cell. I was thinking about getting Onstar with the directions or just getting the Map Disc. My truck is 2004 and this is 2014 so would the map disc be updated to this year and is it updated every year? Would I look for a disc for my year model or should I just get Onstar for directions. I don't want to change my radio because there is nothing wrong with it...it's just missing a map disc. If I go with Onstar, I have to go to the dealership so they can change the equipment from analog to digital and then sign up for a required one year subscription for $399. Any suggestions? Thanks!