Wow.. lots of pre-'06 guys trying to justify their dated truck looks! (I KID, I KID!! -but you know i am right!)
I'm actually posting on this topic about the navigation.. I'd honestly recommend you get the truck that appeals to you most.. don't do it for it's nav package. I have a Garmin Nuvii 660 that blows the fricken doors off of my '06's nav package.. plus it fits in your jacket pocket to be moved to any of your vehicles.. Go that route!
Oh.. just wanted to add that the nuvi both transmits on it's own speaker or it has a built in FM modulator to play through the truck's stereo.. also has the FM traffic alerts that allow you to bypass congestion/traffic in the bigger cities, and holds a gazillion mp3s.. ok i am done now