4 bolt question

[Savage Talon]

What part of the 4 bolt is stronger then the 3 bolt. Is it the shaft itself? Is the cup that goes into the diff made from a diffrent material and/or bigger? I ask because when I break rear axles I break the splines off in the diff. So if the cups are no stronger I don't need to change the rear end, just my bad driving habits.

 

[Michael Z.]

The VFAQ has a good visual comparison: 4 Bolt VFAQ

 

[Savage Talon]

Thanks that helps a little but still does not show thw splines that go into the diff. That is where I break my 3 bolt axles at, in the diff.