It's oiled by atmospheric pressure, an oil mist from rear drive is to come out of a sliver opening on top edge of the forward pinion bearing travel up shaft & go through the splines inside carrier bearing to splat on the ujoints.
Hope this helps.
If yours is dry, I'd soak it for a day OR take it apart & grease it(good luck). If you pack it full of grease on the outside it will fling off & stick to your boot.