I had lots of creaking from the dried out old bushings
for the sway/anti-roll/torsion (pick your term...) bar.
Changing these eliminated about 95% of the noise from
the rear suspension.

The good news is they are dang inexpensive and easy to
change. Think $5 and no more than an hour of easy work.

The sway bar bushings can really transmit noise into
the cabin. Unlike most of the rear suspension, they are
mounted to the cars body, rather than to the rear subframe,
which is insulated from the body by rubber mounts.

If you get a lot of noise when both rear wheels move
in tandem, as over a speed bump, then the sway bar
bushings are suspect.