As Dave says these babies are all unique, perhaps because they are pretty much build by hand, and unskilled hands at that. Mine is a 2004 production and had Sand, misaligned rockers, non rotating tappets, a defective wet liner and finally my idler gear after having run the stock one for a while, was showing wear on the sides of the teeth. That will definitely cause stress risers and in fact the edges of some of the teeth were already chipped after a few hours run time.
But my roid is out in the genny shack chugging away charging batteries and heating the house as I type. It's burning a nice mixture of B100, WMO and RUG and doing it quite reliably since I've learned to clean the injector regularly. Like George B. says the sound of the engines is awesome and I'm hooked. Currently 1335 hours on mine.