I have no idea what kind of nuts I'm actually supposed to use with this
fence, nor where to buy them.

In preparing to attach some shop-built accessories to my fence, I needed to
solve this problem. No off the shelf hex nuts seemed to fit without
spinning, so I fired up my metal bandsaw. I cut some 3/4" wide 3/16" thick
cold rolled steel bar stock into suitable widths for a loose but "tight
enough" fit in the tracks, then drilled and tapped them for #10-32 machine
screws.

It proved to be a fun project for my kids to participate in, and I
manufactured way more than a lifetime supply of these things. If anyone is
in need, I'd be happy to part with my extra stock. They're not made to
ultra high tolerances, but they should do the job. (You supply your own
#10-32 machine screws of suitable length for whatever application you have
in mind.)

Email if interested.

--
Michael McIntyre ---- Silvan
Linux fanatic, and certified Geek; registered Linux user #243621
http://www.geocities.com/Paris/Rue/5407/