Up for sale is a SLS suspension pump, out of a 1985 300-TD Wagon.  Mercedes.  Good working unit, I saw this cars SLS function, worked well even when we had 3 engines in the back of the car!  Sadly, this car died due to rust just a few years later.  This SLS pump works great, retail price is $1300.  These units can last the life of the car, so long as they are not run low on SLS fluid.  If they do run out, they will get damaged within just a few hundred miles of normal driving.  This unit was removed from the car with a full tank of fluid, and the SLS worked well till the very day this car was parted out.

You should have the same service life out of this as you would get from a new unit, this unit was never run low on fluid, this was in my personal car!