The auto locking hubs only work with the open diff. The drag of the posi keeps them engaged all the time.
Warn made them. You could probably snag a set from an '86 full size in a junkyard. You will need to take the wheel bearing retainers as well. there was something special about them. the instructions on all the aftermarket hubs would tell you that you need ro replace it with a normal wheel bearing retainer. From working with another style of locking hub I know that the locking mechanism has something to do with seeing the axle rotate in reference to the fixed part of the spindle, hence the need for the special bearing retainer, the hub would need to see the axle rotating to drive the lock into place.