Makes sense. Just figured it would bend beyond where the shock mounted, but perhaps that area is stiffer. Could have been from when I had 1/8th scale shocks on it that were a bit long... will see how the new arms do as I have the GTR's with VDK in them on it now. It's relatively soft.was sitting here trying to picture your a arm in my head and how it got those stress marks. try to picture this in your head. your wheel would essentially be the handle end of a long lever. Your shock mount would be the fulcrum. the other end of this lever is essentially attached and non-moving. yes there is a hinge pin but it does not allow it to actually move in an up-and-down motion on that side of the lever. what you're seeing is not a stress mark from the arm bending, it is a stress mark from the arm tearing. essentially the arm is ripping instead of being bent. does that make sense. of course they make the holes for the shock mount with more meat around them in order to create less stress at that point.