In reply to your PM...
They mount to the pinch at the lower part of the body with a backing plate that leverages against the backside of the sill area. It may not seem very strong, but I am pleasantly amazed how strong it really is. These bars are mounted far more securely than the frame-mounted Smittybilts I had on a previous truck, and as strong or stronger than other mounting variations I've seen.
It's hard to really describe how they mount without pictures because the description doesn't do it justice.