I needed a servo-mount for my i3 rework in order to use autobed leveling. This is the outcome. It is not 100% accurate because i measured everything with a ruler. You may have to use a little force to push the servo through its slot. But it worked for me.
The i3 rework is based on ch1t0's extruder, so if you are using this kind of extruder it should work as well.
You also need Zennmasters Z-probe holder and maybe longer bolts for your X-Carriage + two nuts