Object Replacement Tool is an editor extension that I programmed for Unity 3D, it is designed to make replacing GameObjects in the editor a breeze. It replaces objects quickly and easily without the user having to reposition by hand. Just select an object (or multiple), drag in the replacement and hit the Replace button. It also features the ability to add objects without replacing the selected reference, and even allows for mass object placement at incremental position, rotation, and scale.
Asset Store Link: https://www.assetstore.unity3d.com/#/content/6472