I think you'll find its more complicated than just replacing the self leveling shocks with regular shocks.
The shocks you have are able to level the car because they actually support a percentage of the weight of the car... regular shocks do not...
So, I'd expect if you want to change out to regular shocks in the back, you'll also have to change the rear springs, etc to carry the additional load.
Hope this helps.

__________________
KenP

1996 S500 W140 Coupe