Try putting in six and look at the dipstick. You will be ~a guart low. Most dealerships don't know oil from gasoline!!
BTW, it's 6.9 for the "sport" models (as they have an oil cooler), and ~6.5 for the non-sports. I regularly put 7 in my 2 V6 LS's (with a filter change, of course) and the oil level is right at the top mark on the dipstick.