The housing is much stronger and doesn't deflect under shock load like an 8 3/4 does. And just bigger everything, The 8 3/4 is great for what it was engineered for, the Dana 60 was over engineered for a heavier application than the 8 3/4. The Dana 60 is 50 lbs heavier than an 8 3/4 and people say it takes more power to turn but I have seen a few tests that swapped between them and the ET's were the same.
Sheldon