Hey Horacio, I sure hope you did not buy a Z66 for the load leveling shock system. Sounds good in description, but actually I think it sucks when you think of the principle and I think it is a bad thing GM did as a come-on to get people to buy the Z66. I bought the Z66 mostly for the locking differential and the rubber floor mats that came with the option. In theory shocks are to control bounce and hold the tires to the pavement, NOT CARRY WEIGHT. Springs or Torsion Bars carry weight, not shocks. If you give it much thought, think about what holds a shock in place. A single bolt on the bottom and the top of the shock, therefore you are trusting all that weight on either of the 2 bolts. Either of the 2 bolts break, the load is going to fall onto the springs anyway. Just not trustworthy to me. The Envoy uses an air bag system that works in conjunction with the springs. That is a real supporting system that I would trust up until the airbags and lines became dryrotted.