Hi Skipe. Yes, the factory lug size/thread pitch etc., is 14 x 1.5. But "14 x 1.5" only tells us the size of the hole in the lugnut and the thread pitch.Yes, just need 14mm by 1.5 thread. I have Spline drive Gorillas on both of mine, Only issue is they don't hold up in our part of the country with the salt we get in the winter, tend to get rusty. The regular Fusion's use a 12 by 1.5 thread.
However, getting the correct lugnut entails more than just the lug size/thread pitch (14 x 1.5).
There are different types of seats/bases on lug nuts, which fit different types of wheels (mainly the wheel/lugnut mating surface). Our lug nuts are referred to as "bulge acorn type" and/or "conical", with a 60° tapered cone base. So when buying lugnuts for the factory wheels, we must be sure we buy that type.
So yes, the 14 x 1.5 sizing stays the same for an aftermarket wheel. However, when properly buying lugnuts for an aftermarket wheel, we must be sure to ask the manufacturer what type of 14 x 1.5 lug nut seat/base they require to fit the their wheel/lugnut mating surface properly. Most will use a "bulge acorn type"/"conical", with a 60° tapered cone base. But not all. Therefore, it is better to ask before buying.
Hope this makes the information in my previous replies more understandable. Good luck.