As with helper springs, the installation of an add a leaf spring kit is relatively easy. Basically, the process involves adding an extra leaf to the leaf springs that are currently under the rear of your truck. In addition to the kit itself, you'll need a jack and a pair of jack stands, along with the basic tools for tire removal and leaf spring modification.
For starters, the truck must be elevated off the ground to a height that will give you full access to the rear leaf springs. To achieve this, jack up the truck at the rear axle, place the jack stands under the vehicle for further support, and remove the first tire. It's best to perform the installation on one side at a time. That way, you'll have an intact side to turn to for reference in case you get lost along any step of the way.
Next, remove the U-bolts and the lower shock bolts from the chosen side of the rear axle. If you opt for a large add a leaf lift kit, you'll want to have plenty of room between the spring perch and leaf pack because this is the spot where the additional leaf will be placed.
The next step is to tightly clamp the pack, take out the centering pin and slot in the additional leaf. With the add a leaf in place, put the centering pin back through the newly improved leaf spring. From there, reassemble the other parts to that side of the rear axle and repeat this process on the other side.