The Link Object Data operator in Blender found in the Link/Transfer Data menu by pressing Ctrl L in object mode allows you to connect or share the mesh data of the active object to the other selected objects. This is really useful for modifying existing arrays that no longer uses the array modifier because it has been applied - usually from exporting. It is also great for replacing the mesh data of proxy meshes; for example, you were using cubes to represent trees to make the scene lighter and i