You've still got tail lights, right? Pretty common for the "instruments" fuse to just run the gauges, but the tail light fuse to run the tail lights AND dash lights. I can't recall when they started that, but I know it was so by the mid-80s.
On my '03 (actually '02 electrics, though), my dash lights kept going out randomly, due to the taillamp fuse blowing randomly. Turned out my trailer wiring harness was drooping behind the bumper and occasionally coming into contact with the exhaust pipe, with its insulation already melted through.
