8 3/4...School Me...

Well, the 489 and 742 cases are the strongest. Mopar patterned their aluminum chunk on the 742 case because it has the largest rear pinion bearing of most any passenger car rear end, even the Dana 60. The pinion size isn't an issue because even the 742's 1.75" diameter is larger than a Dana 60. But the 489 is more than capable of handling anything you'll throw at it.