In the interest of safety, I am currently considering modifying my factory steering shaft(s) on my '64 CS to include a Borgeson vibration U joint instead of the original rag joint.  I am curious as to whether or not any of you have ever taken apart the factory universal as shown in my picture.  I am planning to remove this universal and replace it with a Borgeson universal joint.  I am considering having my original 3/4 inch round upper shaft which runs from the steering wheel through the column to the black universal shown in the picture milled to a Double D to accommodate a DD universal.  I have read and heard much about not welding or bolting a universal joint to a round shaft.  If I could get the bottom portion of my original shaft milled to a Double D, I could then easily add a collapsible double D intermediate shaft which would fit into the vibration universal which, in turn, fastens to the steering box.  In the event that I don't use my original upper shaft, does anyone know where I could purchase a new 36 inch shaft which has the splines and threads on the end which feeds up the column to the steering wheel?  Any suggestions or feedback will be greatly appreciated.  I know that the obvious option is to leave things alone.