John,
This is a Grizzly mini mill. I saw your X3 and was very impressed. I have small motors on this so I kept the gas strut on the head but mounted on the outside on the left. You can see it in the top photo. I got roller ball screws and oversized ballnuts which I ended up with less then .0005 backlash on the x-y. The z mod I was not happy with I ended up with .002 backlash and it is all in the fixture and not the screw. The rotary table is a Phase II that I modified.
Dan.