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A monotube shock is just that- the shock body is one large fluid filled tube with a piston in it that is attached to the shock rod. The valving that controls the damping is inside the piston. In the case of the Eibach shock, the piston has holes that fluid can flow through and the size of the holes control some of the damping force. On the piston, there are two stacks of thin stainless washers that block the holes. The stack on the rod side of the piston controls the compression damping, and the stack on the other side of the piston controls the rebound damping. The thickness and diameter of the stacked washers control how hard it is for the fluid to bend and move them as the piston is pushed through the fluid.
The size of the holes in the piston and the washer thickness and diameter in the stack controls the damping property of the shock. The shock is tuned by messing around with the hole size and washer stack, also known as the christmas tree.
The Eibach Pro-Truck rear shock has hard polyurethane eye bushings instead of squishy rubber. The increased bushing stiffness means that as much suspension movement as possible passes through the shocks valving instead of deflecting rubber. This gives more control and can actually improve ride comfort as well.
Our F150 is a typical several-year-old truck. Howard first jacked up the truck and removed the wheels to access the shocks. 
Howard loosened the ball joint nut then hit the side of the spindle with an air hammer. This broke the tapered shaft of the ball joint loose right away. You can also do this at home with a large regular hammer.
