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I know some have aluminum control arms, knuckles and some have steel. I was referring to the front suspension parts that control the ride (coil springs) and they are the same other than shocks. All your getting in the Z71 package is rancho shocks, a transfer case shield,hill descent control, high capacity air cleaner and a Z71 badge that was a $430.00 option on my truck. This is the first GM truck I have owned since a 1995 silverado I purchased new and will be the last. I will be moving back to a F150 or Tundra soon.