Convert script to rotate on Z axis

I have a script that will rotate my object in the X axis. I need it to rotate on the Z axis instead and i cant figure out how to do that.

using UnityEngine;
using System.Collections;

public class TextSpin : MonoBehaviour
{

    public float _Angle;
    public float _Period;

    private float _Time;

    // Update is called once per frame
    void Update()
    {
        _Time = _Time + Time.deltaTime;
        float phase = Mathf.Sin(_Time / _Period);
        transform.localRotation = Quaternion.Euler(new Vector3(0, phase * _Angle, 0));
    }
}

Thanks in advance!

@pcdeloney
I think transform.localRotation.z will get you there… or this —>(0, phase * _Angle, 0)); part of your code corresponds to x y z--------- where x=o , y=phase * _Angle, and z=0… so instead of z equaling zero, I think putting “phase * _Angle” there instead may work…