Nakamichi MC1000: who designed and built it?

Probably have to see an exposed motor (cover off the cart) in order to guess any more about it.

I understand curiosity in general but more so in particular. In
this case I think that MC 1000 is an excellent cart. Nakamichi own
story that they worked 2 years on design is less interesting. 
American companies ordered in Japan Miyabi, Zenn, Monster 1000,
etc .,  and sold under their own name so why should an Japanese
company not do the same? While meant for ''professional'' use,
the cart was big succes so they ''produced'' MC 500 for the 
''simple mortals'' or ''poor man Nakamischi''.

My thoughts exacly. There are some cosmetic cues that suggest it was made by Supex, presumably to Nakamichi's specifications. Something they did for numerous others. But I wouldn't be at all surprised if they also hired one of the established designers like Ikeda, Takeda, Sugano, Matsudeira, Ozawa or Nakatzuki to do the design work.

I've even tried to establish if there's a sonic resemblance with the contemporary work of these designers for Fidelity Research, Entré, Supex, Koetsu, Shelter, Accuphase, et al. So far this has been inconclusive.

I agree the MC1000 is an excellent cart, but the included - rebadged - SME headshell does it no service. BTW, didn't Supex offer a similar headshell? Another clue to its origins perhaps?
In any case, it sounds much better in a FR-S/5. These FR headshells has often been called mediocre, but with some carts this reputation is unjustified.

I have owned a Nakamichi MC 1000 for many many years and I also never knew who it was built from, like the younger sister MC 500.
The mystery remains dark.