The written directions from Western Diesel (where I obtained gauges) indicate that the hot wire for the illumination bulb should go to the fuse labeled "ILLUM". This fuse is for the dimmer switch that illuminates the instrument panel. There may be such a fuse for the '03 and earlier models of the Duramax, but no such labeling appears in the fuse box for the '04. When I queried Western Diesel about this, they directed me to the local dealer. I detest dealing with them. Can you help me out?