Ok, it was Water Pump, to my surprise. That's an early failure! We've had no early failures on any of our Police Chargers at work that I know of, and I'm pretty in tune with the maintenance of them. Guess I just had a bad one. It was strange that I could feel it in one of the PCV hoses running off the catch can. Dealership installed new pump and coolant, free of charge seeing how it's only got 4300 miles, and it's smooth and quiet again.

Thanks all.

Larry