Wiring turn signal brake lights

did you check all four wires in the junction? I don't know what colors yours would be but I have dark green and brown to the back lights and light green and tan to the front and indicator lights in the dash. When I try all four I found fluctuating current in all but the dark green wire which told me that the short was in the column somewhere. I have a second harness junction inside the drivers side kicker panel on a 68. Again don't know what a 74 is like but that would be the next place to look but in that case you'll only have the rear lights dark green and brown in my case....