I have a pulsating vibration in my car when I get above 60mph. It shake the entire car, not just the steering, is present when cruising, and not so much when accelerating. I already had the tires balanced, so it appears to possibly be the U-Joints, as suggested by PaulW.

Here is my main question...My dealer just said that they haven't checked to see if that is problem yet, but that it would be $1800 to replace my U-Joints! WTH! That sounds EXTREMELY high to me. Anyone have any knowledge in this area of these cars?

I have replaced entire driveshafts before, and they are only a few hundred dollars. Though be it they were not on crossfires.