the queation i have is when adjusting the preload from a neautal position by half a flat, do you mean shorten or lengthen the bar to acheive the preload?
If top left bar is setting pinion angle;
You make the top right bar shorter to increase right rear and left front pre-load.
You may not need 1/2 nut flat even. Only you can tell how hard it is pulling.
If top right bar is setting pinion angle;
You use the top left to adjust pre-load on the right rear and left front tire by increasing the length.
Ed