Wiring from the CAB back ie fuel pump and lights

The factory didn't do that. They know how to put a truck together to avoid obstacles and pitfalls you and I have never thought of.

There is no diagram that shows every wire in a harness. I wish there was, just for cases like this. That's the way tv and vcr diagrams are drawn, but for cars and trucks they just show one circuit individually. The best way to approach this is to just cut out the crushed section, (be sure to cut each wire back far enough to reach shiny copper), then splice in a new section of the same gauge. I'm doing that right now to a 2011 Dodge Mega Cab that my buddy is extending to install an 8' box. The truck was in a minor crash and the rear harness was torn by the left front wheel. There's 28 wires in that bundle, and even if we had the service manual on dvd, there's over 3,000 pages to look through and the wiring would be on parts of more than 100 pages. Once you learn how to read tv schematic diagrams, you find out that car diagrams are very miserable.

Match the wire colors when you splice in a new section. If you find multiple wires the same color, they are likely going to the same place, like multiple ground wires, but to be safe, wait with those until the end, then temporarily touch a pair together to verify another circuit works properly.

Don't twist the spliced wires like you would with house wires and a wire nut. Push the ends together so the strands slide into each other, then you can twist them a little to help them stay together. Solder those joints, then feel if there's any sharp points sticking up. Flatten those with a needle nose pliers, then seal the splices with heat-shrink tubing that has hot-melt glue inside. Auto parts stores have that. Don't use electrical tape on cars and trucks. It will unravel into a gooey mess on a hot day.