I checked a manual and some post about how to check or change the swivel pin fluid on a 1999 D1 front axle. The housing is supposed to have plugs for drain level and fill. However, my D1 only has one plug, that appears to be near what is probably the level position, next to the wheel stop. The swivel has no oil, but appears to have grease in it. Does anyone have any experience with this, should there be oil or grease in this housing?