After I made the first few cages, I noticed they were really tight around the square nut...much tighter than the originals and therefor not allowing very much play when assembling the cab panels, so I welded some material onto the sides of the cut and ground it down so it was slightly oversized. I used a washer to create some more space in the other direction. The result was much more like the original...with the nuts allowing to rattle in the cage.
Well...that's it....a lot of pictures and text to describe a simple (and fun!) job
Alex
p.s. Square nuts came from the Filling Station by the way.