He said he changed it.

Maybe I dont know. But it's a brand new complete axel.

The other thing I can think of is something is going on inside the differential. Since it doesn't do it when it's jacked up, the only other suggestion would be if you have a friend at an oil change shop. They have those pits you drive over and a guy is inside the pit underneath the car. See if they're willing to let you or somebody drive it back and forth while somebody's under there listening. The problem with that is that there's the damn plate underneath that covers everything up. I don't recommend driving that car with that thing off, as it's also a structural part.

elac had me doing something like that, he said raise the rear of the car and put it in reverse and forward. I did it but the sound was not there doing that. Sometimes doing a left turn at low speed the clunking sound reappear but much less apparent, it seems to be related to something in the suspension.

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elac had me doing something like that, he said raise the rear of the car and put it in reverse and forward. I did it but the sound was not there doing that. Sometimes doing a left turn at low speed the clunking sound reappear but much less apparent, it seems to be related to something in the suspension.

Yeah, it's definitely something that happens under load, so lifting it up won't reproduce it. That's why I was suggesting an oil change place with one of those pits. That is, if you know someone who is willing to do it.

It could be a loose suspension or frame part that flexes under the change in load force. Or it could be something in the diff.

Ok now I understand ''the pit'' I just booked an appointment in a garage who has a pit. My appointment is July 30, that was the closest I could get. Good point piper6909.

Could it be a ball joint? It's a 2002, so after 23 years, maybe the grease in the boot of a ball joint has dried out, and it begins to make a clunking sound, metal on metal, like mine. Anyone has experience that?

I haven't experienced ball joints making that kind of noise when they go bad. But then again, as a DIY'er I've probably have changed less than ten of them on difference cars. Not ruling that out, though. Your appointment was yesterday. Didn't they find anything?

The mechanic was not able to find the clunking sound. He said he does not have expérience with european cars. I booked another appointement with an european specialist. His shop is 1 hour and a half from me. The date is august 5, at 10:00 , thank you for the follow up.

That's too bad. Were they able to replicate the noise, at least?
How well does your e-brake hold? Have you tried going into reverse with the e-brake on, just to put load on it, but not to actually move? If it still makes the noise, you can rule out anything rotational, and concentrate on frame/suspension.
What could be happening is that the load shift going into reverse is causing some movement somewhere. It could be a loose subframe, suspension link, or even a crack in the frame.

I have done the test with e-brake it does not replicate the clunking sound.When doing a left turn sometimes it does the clunking sound. If i’m parked on small slope I unlock the e-brake without the engine running and the clunking sound reappear when the car go back.

I hope it's not a differential related issue, that's what came to mind when you mentioned "left turn". But really strange, I hope you get the problem sorted. Keep us up to date.
Edit: Are you able to perform an oil change on the box to have a look at particles/color etc.?

I checked the oil in the transmission, it was a little low, I ordered from Porsche 1 liter. The car took a half of the liter to be at the proper level (11 mm below the filling plug). It has change nothing, the transmission is still working well.

But did you drain it to have a visual inspection?

I did not drain the transmission oil just add a half a litter to get it at the proprer level.

No I did not have a visual inspection, I was reluctant to drop the oil or change it because my transmission is working really well.

Went to another garage the mechanic said all the rubber bushing and ball joint are good. Nobody is able to find this clunking sound.