This is fixed in the files (CreatureVisual) where icons, texts, and other things are located
at the very bottom of the file there is a piece roughly like this
<MountPoint>
<x>-0.0873698</x>
<y>-0.0181399</y>
<z>1.34409</z>
</MountPoint>
<MountBone>Chest</MountBone>
</CreatureVisual>
these are the hit coordinates and the bone, copy this data from a suitable unit