Rotate Turret back to match base

Hi,

I have a model of a Mech that as the player gets within its range it stops and the top half rotates around and down to track the player then opens fire if the player gets any closer, here is the code I use to track the player -

 // Rotate to face the Player
             var lookPos = player.position - mechTurret.position;
             var rotation = Quaternion.LookRotation(lookPos);
 
             rotation *= Quaternion.FromToRotation(Vector3.up, Vector3.right);
 // Use this line to add X,Y,Z degrees to line up the mechTurret with player when attacking if needed
             rotation *= Quaternion.Euler(XattackDegrees, YattackDegrees, 0);
             mechTurret.rotation = Quaternion.Slerp(mechTurret.rotation, rotation, Time.deltaTime * turnToLookSpeed);

What I want to do is when the player goes out of range I want the top half of the Mech to slowly rotate back to a flat position facing forward matching the bottom half, this is where I'm stuck, I thought something like -

             var lookPos = // This is the part I cant get
             var rotation = Quaternion.LookRotation(lookPos);
 
             rotation *= Quaternion.FromToRotation(Vector3.up, Vector3.right);
             rotation *= Quaternion.Euler(XattackDegrees, YattackDegrees, 0);
             mechTurret.rotation = Quaternion.Slerp(mechTurret.rotation, rotation, Time.deltaTime * turnToLookSpeed);

But I'm not sure of the first part, the Mech is 1 model and the mechTurret is it's Bib-01 Head dragged out of it's hierarchy into a var in the inspector.

Any help will be greatly appreciated, thanks.