Customizing a vehicle such as the GMC can include making modifications to lower the height of the vehicle. Lowering the height of the GMC is done by installing a lowering block that is part of a lowering block kit. lowering blocks, installed at the rear of the vehicle, increase the distance between the leaf spring and the axle, which will lower the vehicle closer to the ground. You can lower a GMC by purchasing lowering blocks that you can install on the vehicle.
Look under the vehicle, behind the tires at the rear axle, to locate the u-bolts that are used to secure the axle to the leaf spring.
Remove the nuts that secure one of the u-bolts using the socket wrench or air gun. Take the old u-bolt off the axle and set it aside.
Raise one side of the vehicle with the car jack. This will separate the axle from the leaf spring.
Place a lowering block on the leaf spring and then lower the car jack so the weight of the vehicle will compress the leaf spring.
Place a new, longer, u-bolt over the axle and hand tighten the nuts on the bolts. Secure the nuts on the bolts tightly with the socket wrench or use the air gun.
Cut off any excess u-bolt that protrudes below the nut with a hacksaw or metal cutting wheel.
Repeat this process for the remaining u-bolts on the vehicle to lower the GMC.
