The truck was having issues with electrical and lights. When I put on the hazards, they blinked. Put on the headlights and hazards, the hazards come on but won't blink. Put on the headlights, the running lights were dim, and the rear passenger turn signal and front turn signal stayed on. So I cleaned all the grounds inside the engine compartment. Cleaned all the lights and the the grounds/bolt/nuts in the light assemblies. The running lights got a bit brighter, the front turn signal worked, but that was it. But then I found a white ground wire on the rear driver's side near the mudflaps and exhaust pipe where the truck bed bolts to the frame. I had never seen that one before. Checked other years ( 73 & 76 ), and that ground isn't there. The white ground wire goes to the rear light assemblies. Both wires look like they were put their by the manufacturer; they don't look like ad-hoc add ons, but I don't know.. I got underneath and saw all the rust encrusting the bolt. Sprayed Penetrating oil and set for a day. I could hear the rust crusting with the turns. The bolt just spins. Sprayed more penetating oil, and it's setting now. The odd thing: There was another black ground wire along with the white wire, and the black wire was just up there, not attached to anything. I swung the black wire length around to see where it MIGHT attach, and he closest place I could determine is on the back of the mud flap attachment bolt ( See pic). But that bolt is rusted and hasn't had anything attached to it for years, if ever. Is that black ground bolt even needed? I suspect it is, and it goes on the rear mud flap area. But it looks like it was NEVER attached, and why such an odd places for both the white and black grounds?