You can always pop the belt off to confirm. I just did the alternator on my LS (burned out and battery light came on) it's not too bad, need to pull it from underneath along with the aluminum bracket - took about 1.5 hours.

alternator swap steps:

-Pull the ground lead off battery (10mm)
-Pull the air intake hose
-Remove the nut securing the PS hose located above the alternator (12mm)
-Lift the car and support
-Pop the lower cover off, and serpentine belt
-Pop the 4 pin connector out of the side of the alt
-Remove the ground strap from back of alt (12mm)
-Remove 3 bolts holding the (aluminum) bracket to the block (15mm)
-Loosen the 12mm nut on the pivot bolt (just to allow it to swivel)
-Back on top, remove the 12mm nut/stud holding the alternator at top lug
-Carefully lower the alternator and bracket down - avoid dropping it on the ground!
-From underneath - carefully remove the alternator in the space between the exhaust pipe and frame

To install, reverse the steps.