After updating my Prusa MK3S+ to MK3.9 I found that previous x-motor cable guide is not suitable. Corners of the original model were cutted for 2.5 mm from each side.
For installaton you still need the screw M3x8 and cable-tie
The author remixed this model.
X-motor cable guide is now suitable for MK3S, MK3S+, MK3.5, MK3.9, MK4.