1998 Chevy Blazer noise and vibration

I have a 1998 ZR2 blazer with only 58K and whenever you go 40 mph or beyond it makes a roaring noise with a lil vibration. All the gauges including the rpms are normal. But when you are going at least 40 and swerve or turn right the noise and vibration disappears. But when the vehicle is straight again then the noise is there. And if you turn or swerve left the noise never disappears. What could this be? Thanks.