I've found that the X Stopper you can download from VzBoT3D Github for RatRig, does not fit the left XY Joiner at all, so I have now remixed it, so it fits.
The author remixed this model.
I noticed the X Stopper from the VzBoT3D GitHub for RatRig doesn’t fit the left XY Joiner, so I’ve remixed it to make sure it fits perfectly now.