k3: Yup I know haha these are from a LTZ. the thing I find odd is they used the FE4 on the 04/05 SS but not 06+There are three different Impala suspension options FE1 FE2 & FE3. The SS and LTZ were FE3. The FE1 & FE2 LT & LS struts and springs will be squishy.
The other gotcha is the wheels. The LTZ has to be setup for 18" wheels to be a donor for your SS. The struts for the smaller 17" wheels will rub on the 18" SS and Optional 18" LTZ wheels and tires.