Some years ago, I got stopped for 'no taillights' on my '63 Effie. When I went searching through the wiring, I found at least a dozen of the sort of 'taps' in which a plastic-covered gizmo is crushed onto a wire to make an off-shoot. The only fuses were a couple on the back-side of the headlight switch. The taillight problem was traced to a pinched wire bundle that was adjacent to the radiator and fed the headlights. (
?)
I used am EZ kit (20 circuits?) for replacement of everything on the truck. The cardboard box behind the glove box door had seen much better days, so I used a pair of drawer slides to make a pull-out that held both the fuse block and the box for my Mallory ignition. And there was still room for a space to hold the papers, etc for the truck. The battery was located in the bed, just behind the cab, in its own box, and I pulled all the wires for the taillights and license light through a piece of flexible plastic tube for extra protection under the truck.
I could sit on the passenger seat and work on the pulled-out wiring array---simply leave enough slack in the wires adjacent to the fuse block. It surely beats laying upside down under the dash.
KS