So I bought a 2010 Tahoe LT 4WD. It says in the build sheet as well as in RPO codes that I have the "Smooth Ride Package"... ZW7. Also has the "Towing Package" Okay... I am trying to stiffen up the rear for towing purposes so I looked into replacing the rear suspension. It did not come with Nivomat shocks, just regular shocks. I crawled under and looked at the tags on the springs and they are #2597850 YAK. These are ALREADY the same springs as the Z71! Question: How does GM sell a vehicle with Smooth Ride Package but has Z71 springs and regular shocks in the rear??? I don't WANT the smooth ride stuff anyway, but I can't figure this out. Any ideas? Also, will the Moog 80169 springs give me any more stiffness than the Z71 springs already on it? PS: I posted this in this sub-forum because this crowd probably knows more about coil springs than the other sub-forums. Thank you!