cwbrak01

I have a 2006 Taurus with the 3.0 base engine, non flex fuel. The alternator was replaced with a Motorcraft re-man, idler pulley replaced with a Dayco, the tensioner assembly and pulley were replaced with the Goodyear versions and serpentine belt was replaced with the Goodyear Gatorback. Immediately after replacing the tensioner and belt the squeak is gone. In its place, however, is a nice slapping or rattling sound. The rattle only takes place when the car is in gear, at idle, and the AC is turned on or the wheel is turned. What is causing this rattle? I have a few theories. The OEM tensioner has a steel pulley and the Goodyear has a composite or plastic wheel, I was told that could be it. Another theory is that, according to the model number, the Gatorback is 85 1/2 inches long while the OEM motorcraft is just under 85 inches(the gauge on the tensioner shows at the top of the acceptabe range) thus the difference in belt length is to blame. A third theory is that the Goodyear tensioner doesnt have the plastic sleeve aroud the bolt to preven rattling. A fourth theory is that the power steering pump is getting weak, although fluid level is fine, there is no leak, and there is no whine. Interested to see what the experienced people here have to say, hopefully someone can shine some light on the problem. I'm brand new to the boar so my apologies for the long post, just wanted to provide detail. The car is a 2006 base model Taurus with 72,000 miles. Thanks in advance!