Help me with a Fidelity Research FR64 part

google translate:
"thingamajig - used to refer to or address a person or thing whose name one has forgotten, does not know, or does not wish to mention."

Normally a nut is something that looks like a nut, i mean the shape of that metal part designed for use with conventional wrench to tight it up. And the FR nut from the stock armbase is exactly a nut.

But the "Arm Stabilizer Nut" (aka N-60) is something much bigger and completely different shape.

Something that often called Tonearm Stabilizer does not looks like a nut at all, it’s huge and superheavy, here is one original stabilizer for Luxman tonearm designed by Micro Seiki. I would not call it a nut. The mass, material and size specially designed/chosen to control resonance. 

Fidelity-Reseach B-60 is not just an arm stabilizer, but a VTA on the fly, here is one.

Ummm... Chak, I was just trying to be funny.  And I partially disagree with that definition of "thingamajig", having heard and used the term since the 1950s.  It refers to an object the correct term for which one either cannot recall at that moment or one does not know.  It's a useful shorthand that dates at least to WW2 military, if not before.  (I learned it from my WW2 veteran uncle when I was a very young child.)  I believe it to be American slang, but it could have emanated from England as well. I have never heard it used in reference to a person.
By the way, it's a "nut" in the sense that it is threaded and the use involves its capacity to fasten two things together.

Can I just say thanks for the efforts, links advice, and then intervention of Chakster!

My next point is this.

My machinist is actually very good, but the FR uses a 25TPI thread which is not standard, not only that but the base is something like 29.37mm diameter - 

 Based on my prior experience with re-tooling for Fidelity research and technics products, I guessed earlier that it is metric. 25 threads per inch is just about one thread per millimeter, which is a standard for metric. The thread pitch is 1.0. Of course, I am not there, and I am not a machinist. I don’t want to step on his toes.

Most of the machinists i have met are not interested to make just one small part, it is not interesting for them and they are busy with some serious orders. Unfortunately we're not their customes with one nut or one screw or anything like that (cheap parts).