Ah-Ha !!! I didn't want to be the one to say it, just wait'n for somebody else to point that out. Yes, the Ford used a little better gear (I believe the Fairlane above was 3.08) than the 2.76 geared Duster's. The 289 was a very short stroke and needed a touch better gear. However, the Dusters would take the 289's in the 60 ft by a fender, but the 289's would wind and pull back around. I think the larger CFM carb played tribute.