holy crap... not only am I a jackass, but I must be smokin' crack... I just realized that the two 'cups' are just the damn housing... the actual differential is the case inside with the gear attached to it... man..
So, to put the icing on the cake, I cleaned out all of the grease that was inside the two housing halfs because I thought this is where you put the diff oil. Can I just put a little automotive grade axle/bearing grease back in?