Neither. Looks like it was machined as a solid piece. You can see where the backside is machined out. I just measured... the "stud" is 12mm and the hole is 10mm. You could cut the stud off flush, drill through from the back and tap it for a 12mm stud... or just a bolt for that matter. If you wanna do some welding, I could send ya this one...Is it a stud threaded in or is it pressed in.