Yup, that's what I think. I had an original '65 Dart GT 273 4bbl with factory A/C that came with manual 9" drums. It was an earlier build, but I don't remember what it was. The later build Barracudas, Darts, and Valiants with V8's I had were all 10" drum. I'm not sure when the cut-off must have been.