Hello again, all my Miata friends;

My 96 M Edition started making a groaning noise recently, from the
rear of the car. You can place your hand on the body just above either
rear wheel and press slightly and the car will groan. When driving it
groans and I'm sure that it groans more, but road noise obscures the
sound. It never gets to be a din, nor does the noise change much. But
it seems definitely to be related to suspension travel, not wheel
speed or engine speed.

This car has 130kmi on it and I am the original owner. Well cared for.

I have third-party replacement shocks on the car. Good quality, about
60kmi on them. The only thing I can see about them are that the boots
are torn. Otherwise, they seem to be working fine. And I've never
heard bad shocks make a low groan like this. Just bottoming out
noises.

I jacked up the car. No obvious leaks from the shocks. No obvious
damage to the alignment joints on the rear suspension. No squeaks or
rattles from the exhaust and the muffler hangers look good. The anti-
sway bar bushings are definitely worn, but with the car up on the
jack, I haven't been able to move the suspension enough to create the
groaning noise, so I'm stuck. Everything on the suspension, except the
shocks and tires are original. I haven't had an alignment recently
that would coincide with the beginning of the noise.

Any guesses on the source, or advice on what to do to make the groan
and isolate the source? Thanks in advance for your help.