Basically the throttle stop hits the outer edge of the 4500 flange rail. Since its wider. Where the throttle stop rotates on the butterfly shaft. It can be corrected easily with a 4500 spacer and a carbide bit in a Bridgeport, or carefully by hand. Im on my phone now, but I will do up a pic tomorrow. Its just not a direct bolt on to the dominator flange, so I wanted to be up front about it and get it out there.