These are from an 84 van. An 84 truck should be the same.
Click on the pictures to make them bigger.
Most likely you have a blown fusible link. They come right off the (+) battery terminal. I once bought a 78 Dodge van where none of the electrical worked and the previous owner had poorly rigged up a points ignition to get it to run. I traced all the electrical problems back to a blown fusible link. A few dollars in parts and about 20 minutes in labor later the electrical systems on the van were fixed perfectly. I later dumped the points ignition for an electronic ignition system.