Ford Repair: brake lights and turn signals, haynes manuals, flasher units

Question
75 F100, 390 ci, 4WD, manual trans.  No brake lights, no left rear signal, no right front signal, no rear "E" flashers.  Left front, right rear and front flashers all okay.  Fuses/bulbs/flasher units okay.
I don't EVEN know where to start.  I appreciate ANY and ALL suggestions.
Thx,
Sinman

Answer
Sinman:

I would start with the wiring harness that runs to the rear of the vehicle.  Haynes Manuals should have a decent wiring diagram available to help trace the wires from the cab to the rear.  Outside of the lighting it sounds like a fun truck.

Patrick