The Bilstein B4 24-011846 is a rear OE-replacement shock for the Mercedes-Benz 300SD base sedan. The BILSTEIN B4 is the OE replacement shock absorber, built to match the original part's specification and function. Made to OE standards in monotube or twin-tube form to suit the vehicle, it restores the ride, handling and safety the car had when new. Against a cheap generic unit, the case for this part is its gas-pressure damping, which holds damping force steady from an empty car in town to a full load on the highway, a useful trait on a heavy diesel sedan. Bilstein's B4 series also carries a limited lifetime warranty, which helps justify the price. Fitment is the part to confirm before ordering. Application years vary across sources, so check the manufacturer's application guide against your VIN. The W126 rear swap is a manageable driveway job. Owners on user forums describe it as straightforward, though one notes that a helper comes in handy. Searchers looking for a 1981 300SD rear shock replacement, W126 rear monotube shock, or Bilstein B4 OE gas shock for a standard-suspension diesel will find this part's application well matched.
The manufacturer positions the B4 as a replacement built to original specification, so it is intended to restore factory ride and handling rather than to lower the car. Confirm with the manufacturer before pairing it with non-stock springs.
Application years for this part vary between sources, so the safest step is to check the manufacturer's application data against your chassis and VIN before ordering.
Expect a moderate, two-person driveway job, and do one side at a time. On the rear shocks, you'll have to pull your rear seat out to get to the locking nuts on the top of the shock. The tops of the shocks are hidden by round, white, plastic covers. The upper nuts are 17mm, and the two 17 MM lower shock absorber bolts hold the bottom. Support the trailing arm with a jack or jackstand so the shock can clear the body. Watch for seized hardware: one owner broke one of the 17mm bolts holding the shock to the trailing arm, and another recommends penetrating oil, noting kroil is your friend.
