Splinter-  I too was surprised at the prices for the special nuts, and also located the lower cost ones on Amazon.   I’m planning to use some of the ones that drop in so I don’t have to slide the bolt from the end of the track.  

Eric - it’s been a bit of trial and error to arrive at a good solution, but I’m satisfied with where I’ve landed.  

Steve - thanks.  I’ll be watching for what you come up with.