I drove a 2010 GT Prem. Saturday and loved it. On the window sticker it listed the 19" wheel pack, Comfort pack and a 3.55 gear ratio with limited slip diff. Don't all the GT's come with the limited slip diff. or is it only available as an option with the 3.55 gears. Looked at another one and it had the 3.73 gears but did not say it had the limited slip diff. Anyone know. Thanks