I have purchased a 2006 G35 Awd Sedan with 11,000 miles. Since it has LOW mileage should I go by the miles or the age of the vehicle when determining at what point to change transfer case and trans fluids . Opinions anyone?

A vehicle that sits idle is almost as bad as one that's driven every day when it comes to drive train fluids. I'd change all fluids now and every 30K miles there after, with the exception of the AT which I'd change once a year! If you live in a warm area of our country like I do, it's cheap well spent insurance!
Gary