I have only seen 1 broken Dana 60 before. 35+ years ago, a rather large guy came in to shop, dragging his Hemi car in. He pulled out of the trunk, a mangled propeller shaft that still had the front half of a Dana 60 and rear half of a A833 still attached to it.
No mention about what happened (and he was big enough that no one in shop was going to ask any questions).
Other than small differences – I do not see how there would be much efficiency difference between the 8¾” vs. Dana. I won’t get into an argument about it (I have 0 facts to agree or disagree).
That said, I do hear a lot more from racing circles, the 8¾” does flex a lot more (under stress) and people are having a lot more breakage with the 8¾” in high HP cars.
If I was racing full time, the Dana 60 is the only way to go (and can still be made brand-new to custom order).
For my needs, the 8¾” will work fine (even though I’ll have big block(s), I don’t plan on high HP or high RPM).
BudW