1988 GMC Sierra Brake lights, directional (front&back)

I bought a 1988 gmc pickup, and I am trying to get to the bottom of the lighting issues, I have checked all the bulbs, fuses and, wires, in the right rear light, I only have back up, and running lights, no brake or directional, up front right, I have no headlight(high or low) no directional but I do have running and hazards. On the front left, I have everything except directional. The left rear has everything, but when the right directional is activated, it binks 3 short times, and 1 long time. I hope you were able to follow all that, and I really hope you have an idea of where to start.