One of the easy ways to thing about the items that are black is they are non model specific items that may be on other models of Ford that don't use any Grey trim. The door handles, the wiper arms, antenna and bezel are all used across different models. So Ford just has them done in the Satin black and installs them as is. One item that is not mentioned here that is also black is the lock cylinder bezels in the doors and the hatch also. Again used across different models, etc. Here is an original GT that shows how everything was done from the factory. If you look closely you can see the difference between the grey cowl vent cover and the wiper arm black. You will also notice the black door handles and lock cylinders. I believe the cylinders were actually anodized black from Ford, so it looks a bit different than black paint on the handles and wiper arms. Hope this helps!

https://bringatrailer.com/listing/19...-mustang-gt-5/