ANDYHIS200

Hi guys, Please help me. I have a IS200 auto. Its an awesome car apart from a squeak I have. It happens when i am going along on about half throttle with a slight load on the gearbox. Its sounds like a rotational squeak, it doesn't change with engine speed, road speed, foot on or off the brake, parking brake on or off. I have cleaned all the brakes, checked all the oils. I still cant stop this squeak. it sound like its from the center if the car. Does anyone have any ideas? Thanks!!