Column is cut a bit up from box leaving shaft longer than tube. Cut flats on shaft to obtain "D"/ "DD" shape, possibly can be left circular and pinned, use standard Borgeson ujoint or equiv to donor shaft (D, DD or spline.) Donor column must be correct length so as not to be too long and run into box. If short, add aftermarket shafting. Rubber bushing into original column where shaft exits tube. CPP was going to supply this as I recall or find a bushing from a suspension vendor/hardware store/McMaster-Carr, etc.
http://www.classictrucks.com/tech/1112clt_three_in_one_tilt_column_install/cpp_steering_column.htmlThey removed the shaft and had it machined to fit Ujoint/coupler. that would also give you the opportunity to match a bushing to a certain machined shaft diameter of your choice. A Teflon or Nylon "bushing" could be machined also or some boot from shock absorber or front drive shafts..........
