Yep Dallas, The 450, & 470 COE steps, are about 3"in. taller, & 4'in. wider, than the steps, on a 350 series GMC, & Chevy COE. The step skirt, is also taller, & wider. The reason was indeed because of a Heavier spec.'d, wider front axle. Frames were also heavier. What's left on that frame, your COE cab came from. Eng., trans. ?