What has to be done to achieve the factory dual alt look,most important the electrical

Check out dmaxallitech site. Eric can fix you up. He is a supporting vendor here.

I have a kit made up that uses all factory parts/brackets/bolts and looks factory when installed. Look here (http://www.gmdieseltech.com/store2/cart.php?target=category&action=view&category_id=2 79)