Attachment rotation

How would you get a attachment to rotate to the direction you are looking in mouselook but only on the z axis?
I have been trying to do this for a few days now with no luck, currently i'm using this.

rotation new_rot = llGetCameraRot() * llGetRot();
vector eul = llRot2Euler(new_rot);
vector rot = <0.,0.,eul.z>;
rotation x_45 = llEuler2Rot(rot);
llSetRot(x_45);

This just gives me odd rotations and trying to figure this out is going drive me insane I need help!

Are you referring to a HUD attachment, like a radar kind of thing, or an attachment elsewhere on the avatar?

I ask because it's not possible to set the world-relative rotation of an attachment on the avatar. Well, I suppose it might be if you attached it to the hips and never played any animations that changed that, but for all practical purposes it's not feasible.

It's attached to the stomach and yes there is a animation the stops all movement, also it's for a tank so you are sitting in a vehicle.

Edit:
My friend helped me out with this, now it dosen't work but its closer than I got

rotation rot = llRotBetween(<0.01, 0.0, 0.0>, <10,0,0>*llGetCameraRot());
vector r2 = llRot2Euler(rot)
r2 = <0.0,0.0, r2.z>;
rot = llEuler2Rot(r2);
llRotLookAt(rot, 0.1, 0.1);

The problem with this is it only works when I face east, if I turn the tank north then look north in mouselook the turret looks west, if I turn the tank west and look west in mouse look the turret points east, Getting the idea?