Hy CORPO, I think the "dished cap" is the inner hub seal o.e.m. p/n 3681195 = National 5850. If there was grease in the hubs and it is meant to be that way, then there should be some sort of seal at the outer end of the hub, to keep the oil in the diff. from washing out the grease. One method of doing this was to have a "rubber seal" in the outer wheel bearing adjusting nut, but as far as I know those have been made of unobtainium for awhile now, hope that helps.
