I too would run the 741, never seen one break the pinion shaft, have seen teeth broke, but that's all 8 3/4's.
That's the pinion deflecting. the 9" has a support bearing on the end of the pinion that prevents this.
Yes all 8 3/4's suffer from it, the case is big part of the problem. The 9" is a great desigm, just not super strong in stock configuration. I broke two in four wheel drives, one busted the internal housing around the tiny support bearing.
