Customized Z axis upper holder for Geeetech Prusa I3 with ball bearings

Had a couple of 608zz ball bearings in surplus. I have used the original from @bigsteve for awhile, but the z-axis lead screw kept wobbling at the top, which I would like to restrict for some tests. So made this remix where ball bearings could be inserted. Together with http://www.thingiverse.com/thing:2069451 I got a smoother running printer, no apparent z-wobble left now..

I made a couple of extra holes in the right holder, one for the extruder tool that geeetech supplies with the printer,