The sender or switch, activates the dash brake warning light when one half of the braking system fails. The tool " you have in place" is holding the other half of the warning light switch. It is a simple piece of steel with a "V" in the center, there is equal line pressure on both sides of it when braking. If the front or rear brakes fail, the pressure of the working half will force the small piece to one side, as it does it hits the sender completing the circuit turning on the warning light.
You will not need it since your truck doesn't have a warning light. You could rig one easy enough, but usually you know right away when half the brakes quit working!
