an end cap at both ends if the end cap is inserted from the opposite end the end 124 of tube 122 is first formed into a driving configuration by swaging the end 124 to expand the diameter thereof and forming at least one transverse aperture 123 therein preferably 2 or more apertures 123 are formed in the end 124 as is apparent to those skilled in the art the apertures 123 can be formed by any conventional process such as piercing lancing drilling laser cutting etc either before or after the swaging step a cup shaped cap 130 is inserted from the near or swaged end 124 into the tube 122 the rim 132 of the cap 130 has an outer diameter that is less than the diameter of end 124 but greater than the original diameter 128 of tube 122 the rim 132 will frictionally engage the inside surface of the tube 122 preferably at the transition between diameters to seal the end of the tube 122 once inserted the cap 130 closes the end of the tube 122 and the yoke structure 140 can be cast thereon the cap 130 limits the extent to which the yoke structure 140 extends into the end 124 as is apparent the cast material will flow between the inside and outside of the tube 122 through aperture 123 once solidified the yoke structure 140 will have a dowel structure to provide a driving connection with the tube 122 while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment it is understood that the invention is not limited to.