In all fairness guys, zzp more than likely sells 10 times the number of input shafts as intense-racing. Their's bound to be failures.
That input shaft looks like it was broke because of Shock Loading. I'm guessing it either broke at a launch with slicks, or it snapped via a hard downshift.
For those of you that are planning on going balls to the wall, for $75 more its probably better to invest in the 300m input shaft. I know for my mods and future plans, the 4340 should be more than adequate.