Yokomo YR-4 II Direct Main Gear Adapter. It is a direct fit. I printed this off and screwed it on with no adjustments needed. Choose your filament wisely, it has a belt that runs on it so friction will be an issue for certain filaments. I always tap screw holes, its up to you but you may want to do the same or you might get away with just winding a screw into it without, of course the beauty of this is that if you crack it you could always just print another and tap it!

Use the 'Convert to polyholes' setting on Orca slicer for best results replicating the holes accurately.