Name that sound: water pump, P/S pump, tensioner?

[YuCrew]

Looking for opinions regarding the source of the "rattling" sounds I have placed here:

http://home.comcast.net/~yucrew/ML_noise.html

1999 ML430 with 120,000 miles. New fan belt (Goodyear Gatorback) and idler pulley (strictly preventive measure) installed 1,000 miles ago.

P/S pump reservoir is full with no signs of leakage. Sound doesn't change if steering wheel turned full one direction and back to the other. No liquid visible from water pump weep hole. Water pump and power steering pump are original. Cannot determine if the sound is water pump, power steering pump, tensioner or A/C cluth. Sound doesn't change when A/C compressor is engaged.

I don't have a stethescope. Any opinions? Wild a_ _ , educated and experienced guesses gladly accepted. Thanks in advance for your comments and assistance.

Jim