[tractorboy]

also have a 2003 Impala, LA1. Ummm let me tell you what i did a few years back. I had a Chevy Celebrity, it had a squeek , squeek that i was sure it was a wheel bearing. Sometime i thoght it was the front sometimes the back, wait it was on the right, no left. The wheel bearing was about $300 from Chevrolet, so I wanted to make sure I got the right one. So I got a cassete tape recorder ( you could use a notebook, or anything) a mic and some painters tape. I taped the mike to each fender, befor driving with the mic at each location i would bend down and speak intothe mic taped to the fender and say "right front" or "left rear" . I went home and listened to the tape, no doubt now which one it was. Your noise , from what you are saying, sounds more like the transmission
there is also a service letter out , i think, not sure for a whinning sound fromsome Impalas, cannot remember where i saw it or what caused it.