Your old shocks were Nivomat Self-leveling shocks. They have internal valving to keep the truck riding level when you load up, and as such, they actually take part of the vehicles weight. The coil springs on there now are not rated to fully carry the weight of the vehicle. You'll need to return your new shocks (which in reality probably are the right ones, if you didn't have the ZW7 Premium Smoothride suspension [RPO code found in the glovebox]) and get some Nivomat shocks (Monroe does them best, about $340 a pop)