Fairly common problem for your car. Plastic sway bar links connect the metal sway bar to the front of the hub assemblies. They have two ball & socket assemblies that wear out and make a heck of a racket.

I was unable to learn anything about their condition by shaking the plastic links themselves. But ordered them on general principle since they looked really old. However, with the wheel off, I had the leverage to push the sway bar itself up and down and reproduced the noise exactly. Upon replacement, the sway bar clunks were gone. So quiet I can hear the rest of the suspension "complaint" noises.

This is a fairly easy DIY job. Take off the wheel to get good access to the links - they unbolt rather simply.

Ken
'82 300D