These are the measured sizes of the spindlenuts The measured nuts were already non-genuine replacements, so it is possible that not the original size is measured.
The spindlenut of the X-axis gets seated in an recessed hole in the crossplate. At the bottomside is a round stub for positioning the nut.
The spindlenut of the Y-axis gets fastened with an M8 bolt to the crossplate.
The spindlenut of the Z-axis is mounted to the backsite of the horizontal millingspindle.