The Strongest Savage Diff Compilation.

[simplechamp]

I think the fact that an alloy cup is one solid piece is what makes the difference. With plastic cups it's a 2-piece design: a steel insert pressed into the plastic. That joint becomes a weak area and the plastic fails. Either the Nova or IRC cups should do just fine. 6061-T6 and 6082-T6 alloys are both very similar.