used the 8" (or so) of metal strain relief that comes on the lights to reach the cab. The bracket has notches that allow you to slip wire through it, and in the the brake light opening. I then went along the headliner, down the c pillar, under the carpet and through the firewall. The only real bad thing i could say about it is that the gaskets that come with it are only good for 1 or 2 installs. If you put it on and take it off to add or remove items, the gaskets get a memory and you may need to replace them. I just cut some generic material, and it worked just fine. But it has 2 gaskets, one on the inside of cab, one on the outside, so it seals well and never leaked