I have a 08 trailblazer, 4.2L 6. Upon driving I hear a very loud roar, that is speed related. When slowing and braking the noise "winds" down accordingly. I have replaced the fan clutch, and the emissions valves, solenoids, and air pump are all functioning as they should. I seem to notice that when traveling down the highway if I turn the steering wheel to the left the noise goes mostly away. When I bring the wheel back to the straight position the noise resumes and gets somewhat louder upon turning the steering wheel to the right. I had a 07 trailblazer and had to replace both wheel bearings, but I don't recall the loud roar noise, but more of a gravely sound. Could this still be a wheel bearing, or is it transmission or drivetrain related?? Also, I noticed the engine rpm is functioning properly. Any help would be appreciated.