[1971LT1SWBPOSI373]

although it's not likely, it could be the printed circuit panel on the back of your dash panel. What you might want to try is unplugging the electrical connector on the back of the dash panel and checking for voltage at the connector (and rotating the rheostat to watch the voltage climb or drop). If you have voltage present then you have a dash problem, if you don't have voltage then maybe you have trouble at the fuse block. You should be able to find a schematic for your truck in the FAQ section of this board. Hope this helps, TJ