A couple of answers to your posts.
My truck frame is C channel so no spacers required. Phew...dodged that bullet! Also, the shock mounting bracket is multi-curved piece. I suspect it would be difficult to drill accurately to line up with the hole to be drilled in the frame. And the nut just wouldn't sit properly on it.
They used new brackets. However, I'd consider them "generic" L brackets as opposed a model/year specific brackets. My concern with changing brackets to a model/year specific one at this point is it may force a slight change in where the bed rails inside the box sit. This could mean another set of holes in the bed. I realize this probably isn't a great argument.
