tail light wiring mess, help!

[75k20]

got a donor bed for my 75 k20 from a junkyard. trying to figure out the wiring for the taillights and the previous owner did a major hack job.

i have 3 wires coming from the truck,
ones yellow
ones light green
ones brown

i thought there were supposed to be 4 wires from the truck. some of the wires were spliced multiple times making me question what goes where. the bed still had its wiring harness on it with the 4 pin connector, although there are 5 wires going into it.

my plan was to go to a local parts store and buy a new 4 pin connector but i have no idea which wires go where. please help!!

 

[Matt69olds]

Brown is taillights, left turn is green, yellow is right turn. There will also be a wire(usually pink) that is for the fuel gauge sender. Finally, light green is for the reverse lights.

Every square body I have ever worked on seems to have hacked up taillight harnesses. Since I’m cheap, I use taillight harnesses from S-10 or later model trucks and adapt them to the older stuff. It seems the later model trucks usually come equipped with tow packages, the wiring isn’t hacked up. Usually you can find a couple trucks in the junkyards with intact harnesses

 

[75k20]

Brown is taillights, left turn is green, yellow is right turn. There will also be a wire(usually pink) that is for the fuel gauge sender. Finally, light green is for the reverse lights.

Every square body I have ever worked on seems to have hacked up taillight harnesses. Since I’m cheap, I use taillight harnesses from S-10 or later model trucks and adapt them to the older stuff. It seems the later model trucks usually come equipped with tow packages, the wiring isn’t hacked up. Usually you can find a couple trucks in the junkyards with intact harnesses

what do you mean pink wire? my fuel gauge has never worked as long as i’ve had it. am i missing one green and the pink?

 

[Matt69olds]

Sorry, I guess I should have specified the pink will be towards the front of the truck. There should be a light green wire somewhere on the taillight harness for the backup lamps.