'03 G35 Noise - Looking for Help

[cubanobum]

Hey guys, I've got a stock '03 G35 automatic that's making a particular noise when I accelerate up hills, and becomes worse when I have weight in the back seat or trunk. Sounds like it's coming from under the car, below the center console. It sounds like a deep clicking noise. The harder I accelerate up a hill, the louder it becomes. I've read that it might be a heatshield that's loose, but wanted to see if others have experienced the same problem. Bought it brand new back in '03 and it now has about 47k miles. It's never driven hard.

Any help is appreciated. TIA