Dean, On another web site a poster had the same question. He e-mailed Draw-Tite and they said the add on Dual Cam system will work with the round Draw-Tite bars. On the flat ends of the bars, you bolt on the cam and the rest of the system is the same as the square bar type. You can see this setup at http://www.reesehitch.com/sway_control.html
Hope this helps you out.