Unity - Replace GameObjects With Prefab

using UnityEngine;
using UnityEditor;
using System.Collections;
using System.Collections.Generic;

public class ReplaceWithPrefab : ScriptableWizard
{

    public GameObject prefab;

    [MenuItem("GameObject/Replace Selected Objects With Prefab...")]
    static void CreateWizard()
    {
        ScriptableWizard.DisplayWizard<ReplaceWithPrefab>("Replace Selected Objects With Prefab", "Replace");
    }
    void OnWizardCreate()
    {
        if (prefab != null)
        {

            foreach (Object o in Selection.objects)
            {
                if (o is GameObject)
                {
                    Debug.Log("Transform: " + o.name);
                    Transform t = (o as GameObject).transform;

                    Transform newObj = ((GameObject)PrefabUtility.InstantiatePrefab(prefab)).transform;
                    newObj.position = t.position;
                    newObj.rotation = t.rotation;
                    newObj.parent = t.parent;

                    Undo.RegisterCreatedObjectUndo(newObj.gameObject, "Replace Selected Objects with Prefab");
                    Undo.DestroyObjectImmediate(t.gameObject);

                }
                else
                {
                    Debug.Log("something else.. " + o.name + " " + o.GetType());
                }
            }
        }
        else
        {
            Debug.LogWarning("Can't replace with prefab, because you haven't assigned a prefab to use.");
        }

    }
}