I talked to ARB about this and they said that originally that is because of the right hand drive jeeps. You know
@Kiwi TJ style. Both A's go on the right side because most of the weight will be on that side, but here in left hand drive land there is no real rule of thumb. He said you can put them where ever you want and if there is a lean you can swap them to the other side, but he did say that most people do
AB
BA
if you are sitting in the TJ, but that isn't always right. If your truck leans in that formation, then swap them across,
That all said that is exactly how I did mine. I found that interesting.