Ladder bars..??..

Yes
So the point of "binding" is that, that leaf spring is also going to slide back and forth threw that bracket threw a bunch of bushing holding it from side to side motion as well as being able to slide forward and and back threw the floater(my statement was "100 ways to bind")exaggeration but the roller either are going to be tight on the side of the leaf spring(bind) or loose(aka loose trac bar affect)
The leaf spring will slide, up and down, the axle. the slotted plate that i outlined in red. from the pic you posted of the Floater!

Maybe i should rephrase that....
Because of the slotted Plate(Part of the floater kit) that the spring centering bolt will slide forward and back as the spring get longer and shorter as the suspension goes up and down.
Rear shackle will do the same as always.

When i first read slider i took it was replacing the shackle for a slider.......NO slider as part of the floater and retain rear shackles.
I'm just telling you and others, that i finally get that.

Actually, the axle housing moves (rotates) and that’s what the slot is for. The spring doesn’t move, but it does get shorter with more separation and longer with under compression. The length of the spring front eye center line and the center line of the front mount of the ladder bar are two different lengths and that’s why you need the housing floater. It allows the housing to rotate to compensate for the two different arcs of the spring and ladder bar.