because casting is very strength.The url that you have post for me, it's chassis-tech weld I-beams not chassis-tech oe style cast I-beams. Chassis-tech makes 2 models but i think the oe style cast I-beams is discontinuated in cause the highest price. It is for that reason that I look for one set, i don't find it. I saw this product in my old Truckin' magazine