questions on tank turret and mouseorbit camera

My first problem, I have already find a solution in the below link, but the second question rise, I have a mouseorbit camera synchronize to the turret like world of tanks. But, after I use transform.localRotation. Camera didn't synchronize to the turret because when the tank is rotate y axis, the turret also rotate y axis.

http://answers.unity3d.com/questions/685093/tank-urret-rotation-need-help.html

Code with first problem

 function Update () {
 
 x += Input.GetAxis("Mouse X") * xSpeed * 0.02;
 
 var rotation = Quaternion.Euler(0, x,0);
 
 transform.rotation = rotation;
 }
 
 
 

Code with second problem

 function Update () {
 
 x += Input.GetAxis("Mouse X") * xSpeed * 0.02;
 
 var rotation = Quaternion.Euler(0, x,0);
 
 transform.localRotation = rotation;
 
 }