Originally Posted by Ray_Welder
Are those red things straightening the leaves to lower the truck?
As Dustin stated, those are Lakewood Traction bars.
If your engine has enough torque, when the gas is mashed, the leaf springs ' Wrap ' or ' Distort '. due to the axle twisting from the forces being applied to it.
What those ' bars ' do is take the energy and focus it by not allowing the springs to wrap up and ' bounce ' the tires off the ground.