ok thanks.but you could use the steel swedged tubes and not have to cut them or do any tapping or threading.that's what i'm getting at.on ROD END SUPPLY they have a chart for getting the right length on the tubes.they say for 5/8 rod ends you take centerline to centerline measurement and deduct 3 inches for the size of the tube.when i measured the arms they measured 11 3/4.that should call for an 8 3/4 in rod.so i guess a 9 in tube would be the one to use.then when you put the rod end on you would have plenty of adjustment.