Control arms were precision made by a guy that builds jeeps and crawlers. That's a problem I had with the previous pro-comp arms. Most likely the brackets on the axle...but I thought they were jig made or something, who knows the evil robot welder probly moved an inch or two lower

 

I realize you can't literally twist the axle with the eccentrics. That is why I said "effectively" twist. Sorry for the confusion. It was the best way I could think of to express myself.

As for adjusting the caster with the eccentrics, I though it was adjustable? Although I realize it is there primarily for manufacturing tolerance purposes. It seemed to make a difference in my last truck when I maxed out both sides after putting on a leveling kit.

From the 2004 factory service manual:

 

Paul,

The eccentrics adjust the caster by rotating the entire axle housing. They also fit the axle to the truck frame by allowing for some mis-alignment. Camber has to be set with offset ball joints.