Why only two. Axon fits on the xray so the x-rays should fit on the Mugen as well then.
The X-ray Spur Gears does not fit correctly.
You can use 2 Srews but in my Eyes that is not good because it runs not straight at the Point where the 2 Screws missing.
I have testet the Kimborough and the Graupner.
But because they have only 6 holes they do not fit.