The last MOT advised they were due for replacement, "but what do they know". Sure enough two months later the rear near-side was making some mean knocking noises. On investigation the bottom ball joint had parted company completely.

Replacing rear drop links without removing anti-roll bar or getting under the vehicle.
Special tools required.

Induction heating tool. (this is mandatory for working on an L322 as every nut is seized solid with rust)
Large sacrificial nut (make sure you have a socket to fit it)
Welder
Right-angle impact driver

Removing the ride height sensor connection to the lower suspension arm does give more access and reduces risk of damage to this plastic part. 13mm socket with 10mm spanner at the back.

The top ball joint nut on the drop link is near impossible to access so you can't get any torque on it.
Heat the nut with your induction tool excessively and the top ball joint will part company as they are only made of plastic. Put large nut over the exposed ball and weld it on. Now you can get right on it with a bar & socket/right-angle impact driver. Heat nut more and the ball end can be backed out of the nut easily.

The bottom ball joint is far more accessible and you can get a socket on it after applying heat. Forget thinking penetrating oil will help they are useless.

Replace with new drop link assembly.

As the top ball nut is so difficult to access I filed off the nylok end and removed the nylon locking ring. Then used an M12 lock washer (and locking compound if you really want to). This way you can spin on the nut fully without fighting that nylon locking ring. Then it can be tightened fully with a ring spanner. I had to use the induction tool to heat the ring spanner and put a bend in it as it is the only way to get it in there and apply enough torque.

Replace ride height sensor connection.