when you continue to operate the vehicle with bad shocks the springs will be damaged ..as well as other vehicle componets due to the constant movement/friction created...
as the others have stated you now will need new leaf springs and new shocks...If you do carry heavy loads on bad off road get the stronger leafs..
I also have the bilstiens front / rear on my 2000 sil 4X4 ,,,very nice ride and smooth ...