I've not seen any signs of fatigue so far. Mine mount with a beefy L bracket to the side of the frame. I haven't put many miles on with them but I like the improvement in ride. They're mostly to level out the 60 series springs that are under 40 top leaves... not to carry more weight.
I would like to see the upper mount tweaked to be closer to parallel to the bottom.
I would like to see the upper mount tweaked to be closer to parallel to the bottom.