How Many Horses does your Posi eat?

Yup, I saw that too. No difference, performance-wise. Strength-wise?
68 SS Barracuda's and Dart's used both.
8.75" for the Torqueflite cars
Dana 60 for the 4 speed cars

Obviously, the 4 speed cars are harder on the rears so they required the 60 to live.
The only reason's that I can think of to use one or the other are:
*power level and traction - BIG power requires BIG tough rear=Dana 60
*ease of swapping gears - 8.75" rear (keep in mind, you can build a bullet proof 8.75" nowadays)
*vehicle use - handling/road course build, lighter 8.75" will help handling through the lack of overall weight and lack of unsprung weight

Ford 9" - who cares, they just copied the 8.75"....LOL (yeah yeah, I know, great aftermarket support using zero ford parts...still don't want one.)