Ford Repair: 1990 E-150 Cargo Van, headlamp switch, electrical knowledge

Question
Not sure you can help with this as your expertise does not extend to years prior to 2000.  But, I imagine not much has changed with tail lights on this vehicle.

So, the problem: left tail light is out
1) bulb has been changed  
2) electrical contact cleaner applied
3) connector was traced and cleaned.

Brake lights and turn signals work. Tail light is still out.
Any other suggestions?

Answer
your tail lights are fead from the headlamp switch, at nor near the rear bumper, there is a splice that splits to the right and left rear tail lights. not being there so i can see, there is an obvious break after this splice. if you have electrical knowledge, you can jump these two wires from the right tail lamp to the left with no damage