The SS rod is the spindle of a pedal on what Hobie calls a "Mirage Drive":
Basically a couple of pedal-driven flippers that propel a kayak.
I am fabricating new pedal cranks for mine after breaking two of Hobie's.
The SS spindle is 15/32" and I would drill the same-sized hole in the solid 6061.
I do not want to get involved with cutting threads in SS, so I am thinking maybe just put the spindle in there with Red Loctite.
Doesn't seem like there is that much stress on it - and Hobie does something similar where then do a force-fit of one end of the spindle into the far end of their alu box stock.
Does anybody see any hope for this?