I have researched all leading Truck Cap manufacturers, and none have a canopy designed for the 2020 GMC 3500 HD dually with an 8ft bed. My preferred choice would be Leer, but at this point I would buy from whatever manufacturer comes out with one first. I depend on a canopy for transporting Kayaks, one is 19 feet long. I also carry bicycles in the back that would not fit with a Tonneau. Securing loads when camping is also important. I love the truck, but am disappointed that I have now lost all the functionality I had with my 2016 with a Leer cap.