Looking at a number of top box luggage racks for my GA. Have narrowed it down to the Kuryakin Adjustable, Isotta and Wunderlich. Like the idea of the Isotta as you do not need to drill the top box lid. Anyway, my question concerns the inside of the GA Top box lid. When I examined it yesterday, I noticed 4 circular mouldings with a cross in each which looked like a cap that you would unscrew with a Phillips screwdriver or similar. So are these “casting“ marks that indicate where you drill for a top box rack such as the Wunderlich offering or something from another BMW - K1600 GT or GTL for example?