Your traction bar is the suspension link that prevents your axle from moving forward. This modification is a popular choice to eliminate the distortion between the axle and the rest of the truck. By not allowing the axle a range of motion, this brace prevents the changing of pinion angles that can destroy a driveshaft. Bracing the axle minimizes the bouncing effect that leads to driveshaft failure over time. There are all kinds of traction bars available and while the rear attachment is most common, they can be attached to a variety of different places on the axle.
While there are many kinds of traction bars to choose from, the three most popular sizes include Short, Medium, and Long bars. The short bar is used primarily for truck racing and drag racing. They are also called caltracs and are attached to the front spring shackle. The second type of bar is the medium bar and usually attaches near the rear cab mount next to wear the frame begins to bend from the rear. Finally, the long bars are preferred by some and connect much farther up front. These bars are designed to take tremendous amounts of stress and cause the front end to lift. For some this is an undesired effect and the shorter bars are a preferred option. Longer bars require stronger materials due to the increased force being applied to them