Hello Sylvain
Indeed there are inconsistency's which are inherent part of hand assembled devices by small company's.
The level bubbles are also of a completely different design as mine are countersunk into the body.
You will also notice the shutter timing plate is also different.
All these small differences could possibly be attributed to supply and demand issues, improvements or even price.
The nameplate is made from celluloid but a early type as it has a high camphor content.
I first thought it might be of bone or tooth material but testing proved its compound.
It is strange that yours never had one. Maybe supply issue or even made to contract for the government?
Could I ask you to measure the box dimensions of your camera?
The one here is:
Height -18.9 cms
Width - 11 cms
Depth - 23.4 cms
Sylvains unbranded camera:

G. Fournier camera:

- comp1.jpg (35.56 Kio) Vu 5582 fois
There is a manufactures stamp on the underside of the plate release mechanism. This might also hold a clue. I did search it but came up with nothing apart from a Japanese camera company founded in the 1950's. This did not make any sense so I put it down to coincidence.
I will unscrew it again and post it here as I have forgotten what it was.
Also I have never pulled the front off the camera. Clues might be found in there. I will have to do it someday as the pneumatic release has never worked.
Best wishes, Stephen.