Rene is correct. I run them front and rear and I love them. Wouldn't run them on a street truck, but off road, they are the stuff. I used 2.5 x 0.250 square for the outer. It's actually just under 0.250 (around 0.220-0.230) with a swedged out weld seam so the 2 x 0.250 can slide inside. Local steel yard (only 1 out of many carries it) refers to the stuff as "square DOM" but it's not DOM.
With enough overlap, there is very little slop. More overlap reduces the angular variation from one side of the "slop" to the other and reduces vibrations. I've had mine over 45 mph with no issues. In addition to the tubes, I got new weld in yokes from Jess at High Angle. These were notched/ground for a mechanical fit on the square tube, then fully welded in place. Once welded in, the weld area was ground smooth to eliminate any larger mass differences that would contribute to vibration.
Over all I am VERY pleased. No more candy canes for me. In fact, I've landed on them and augured right on through with no damage to the drive lines...
