I'm not sure of a source for the brake cables, but I believe one or two options exist. Search in the Tons 'o Fun section as I expect it has been discussed there.
https://www.stovebolt.com/ubbthreads/ubbthreads.php/forums/45/1/tons-o-fun.htmlGlad you found the seat belt info helpful. Not sure if I mentioned it already but in hindsight I would install shoulder belt, and intend to do so with addition of a mount on the pillar, the other mount locations are unchanged.
Mine will also be a pickup box with single wheels eventually, already running the single wheels. The 18" duals came on my truck. Guess I did switch to 19.5 dual for a while from a GM truck, commonly on 8 lug bread trucks and similar, but somewhat difficult to find these days. likely new 19.5 dual wheels are available if used can't easily be found.
Dual wheels do not fit in the original fenders and pickup box. Some have figured out how to do it but lots of sheet metal work, not at all an easy thing to do. Again check the Tons 'o Fun section.
