For rockcrawling, the shackle reversal is a good idea, at least in my opinion. My 2&1/2" Alcans are somewhat flat on the SOA YJ. The shackle reversal eliminates the long, hanging shackle on the front of the spring allowing more approach angle to avoid smashing into vertically flat rocks. Very few things are as jolting as hitting a vertically flat rock you're attempting to climb over. The Alcans actually move backward somewhat as the tires grip the rock, but it is hardly noticeable. I also have a boomarang shackle on the rear of the leaf springs, it appears to be an improvement over the straight shackle. But, I did have to invent a limiting stop to prevent the leaf spring bundle from bending into a bobby-pin shape for rare climbing situations when the front end is up on the rock and wants to bounce. I also have a limiting stop to keep the tire from rubbing in the rear of the wheelwell, this seems to be mostly a problem descending steep trails that have rock obstacles and/or deep holes.