CDF is 1" smaller in diameter. We will post results just as soon as we go to the field. Factory set up is reccomending a pair on the RH end. We are not running any, but we are in virgin territory here. We are setting up with Steep pitched on the thresher shimmed out .125 w_ helical extention transitioned into the reg pitch on the lH side. leaving out the reverse bars and a short 5"cyl bar piece to prevent wear where the crop divider is located. This would be from the RH end 7th bolt hole where reverse is left out. reason for this is to prevent back bar wear in this area. This is the only area where we have seen wear when leaving bars off. We run our retarder bars in the sep grate. If someone has the technology I will email some pictures to you and you can post. (Being a dinosaur I can barely type. ) Again we will probably have to do some fine tuning, so this will just be FYI. We are interested to see how this compares to our previous set up, which worked darn well. We think the reduced diameter will be the ultimate from Gleaner. We hear good reports from cylinders who have a leading edge more like the conventionals. We will just see. Kind of like waiting for christmas as a kid.