This X table drive was added to the mill-drill when it was acquired ca 1986.  
Literally thousands of hours (mill has been completely rescraped once 
about 10 years ago) with no problems.  I attibute this to 1.) a solid well
aligned box section extension welded up out of aluminum channel.  2.) a bearing
aligned with the needle bearings in the drive to support the extension shaft
and take the eccentric loads off the powerfeed components.  Extension was
designed to be below table surface, and to allow full table travel.