I don't believe they vary, but I could be wrong. They are adjustable, and while the instructions specify a mounting point, you could modify and change the mounting point a bit if your lift was very high. That being said, I can't imagine it being much different at anything under 5 inches.
I would say it doesn't matter. I have the PRG off-road bars which would fit on a lifted or non-lifted truck. Basically, you attach the forward attachment bracket to a different part of the frame depending on the distance from your axle to the frame. With a lifted truck, the forward bracket would be mounted closer to the axle, and a non-lifted the forward bracket would be a little farther from the axle.