kito: Nuts (literally), don't have that size in my notes. And went to MechanicO to measure for you you can even see the threads. It is around 22mm in diameter. The issue you will have is a "normal" nut that size is huge and thick. Probably won't even fit in there. However, you have an option: just make a spacer that goes under the current nut. Make it to the height you want, back the nut down onto it, and now the nut will not strip the threads. Or have a machinist hake you a custom nut. I did this, as well as the two nuts, but in retrospect probably overkill. You do have to do something as it WILL strip with just the nut. I pretty much had TT tell me this when I ordered those parts.