Ah, ok. I basically thought the point of a center diff lock was in the 'lock' mode, it would evenly distribute power to both the front and rear differentials...
You have it backwards, as did someone before you. The purpose of a center diff is to allow different speeds between the front and rear drivelines. It's not a center diff lock, it's a center diff (no lock) to allow it to be "unlocked".
Any tcase without a diff is locked by default.