I myself just recently bought a new pair of Nerf Bars much like you described. They are often referred to ask Wheel to Wheel Nerf bars. And many makers of them for duallys will put in a kick out that allows the bars to follow the body line of the dually. There are way to many manufacturers that make that type bar to list, suffice it to say they can be bought many places for a widely varying amount. I am waiting for my Putco 4" stainless steel Boss Bars to arrive, they are like you mentioned and look awesome with their larger then life 4" diameter bars. In my search I found a good 5-6 maybe more, makers of such bars. They can be found in black steel, chrome, stainless steel, and chrome over stainless. Just do a search under the heading of truck Nerf bars, putco boss bars, or truck bed accessories.
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Like anything else the price varies widely, depending on maker, type matterials used, and length. I personally like the Nerf bars better then any other truck side step, I think they are cool and much better then running boards. The better ones require no drilling and use the body mount as the attachment point. I liked the new ones so much, I decided to trash my current Nerf bars in favor of the Boss bars, anyone need some good but slightly used Westin Nerf bars?