You didn't say if your 93 900 is a 940 or 960. The 940 doesn't have the self-leveling shock with lighter spring setup unless someone spent a ton of dough on the self-leveling dealer added kit. On the other hand if it is a 960 the self-leveling shock (Nivomats, made by Boge) are standard. The Nivomats will settle when parked and not necessarily need to be replaced (though this is usually an early warning of a filure in the future). If you drive the car and go over some uneven surfaces the up and down motion causes the shocks to "pump up" to a level ride height even with 500 pounds in tail end of car. If the car gets level after a 2-3 mile drive then forget about it for now. If it doesn't return to a level attitude then you have a failed shock.