This is the aforementioned purge valve. It mounts in a different spot on the Boss manifold than the stock manifold. In a pinch, you can use a longer piece of fuel hose to relocate the connection. If you want to install it just like a Boss, you'll need to pick up the following bits from your Ford dealer: CR3Z-9G297-A, hose; CR3Z-9G290-B, bracket; and W506974-S437, screw. Ford also uses different fuel lines (PN CR3Z-9J280-A) and induction tubing (PN CR3Z-9B659-B) if you are going for the totally stock look.