I forget what thread it was in but I'll post it here for the masses.

34 ft lbs.

This is with all the disks opposing or 100% lockup. (100% of possible, not 100% locked). Keep in mind it's with no load on the diff so this is a minimum value when you're coasting (not engine braking, not accelerating). It slipped very gracefully but was pretty consistent and smooth. This was the peak reading on my Snap-On Techwrench.

I believe the maximum lockup torque is somewhere between "jesus" and "holy #@!$".