Faults:

Truck had a bumping in the tires, very rough ride, dealer could not find out the problem, service department tried everything, changed wheels, tires, rear end, everything. Could not do anything else to it, still bumping. A friend, and tire specialist, trimmed the tires and that's all it took. Even Chevrolet didn't know what was wrong, said all custom trucks drove that way. Anyway we got it fixed, but not by Chevrolet.