Hi Irinikus,
thanks for responding on rivets, it was a real stab in the dark see if anyone from IRIX Network had touched this.
The pointer to "High Strength Structural Blind Carbon Steel Dome Head Rivet" was very helpful, as I was doing search on "stainless steel 6mm rivet".
This helped me home in on: Huck Magna-Lok Rivets
These are structural steel rivets, available in 1/4" (6.4mm) size and have hollow end, which looks identical to the ones on SGI rack.
There is also Huck / Makita BV4500 Cordless Rivet gun for installing these, but it’s very expensive.
A cheaper option might be Makita DRV250 rivet gun or even manual tool.
I will provide update once I have done some test riveting...
EDIT #1: I have now reassembled rack and am at the point of starting to load the O350 kit into it, here is picture (with intel / linux box installed at the moment):
As this was some considerable effort and I had to learn a lot more than just rivet'ing, I am adding blog post with all the information should another SGI collector want to do this:
https://tips.graphica.com.au/sgi-onyx-35...-stacking/
Once I get all the kit in I will put the front door back on.
Cheers from Oz,
jwhat/John