hello again
I did some more thinkering and I think I’ve found a solution.
gap = thisComp.layer("Null 1").effect("Slider Control")("Slider");
startingPos = [ 0, 240, 0 ];
//--
dispVec = [thisComp.layer("Null 1").effect("xdepth")("Slider"), 0, thisComp.layer("Null 1").effect("zdepth")("Slider")];
i = index - 10;
startingPos + (i * gap * dispVec)