I'm just telling you from my personal experience on switching my own car over from power to manual. The pitman arm I ordered was a new manual arm I believe from moog. I had acquired the manual box I first got from a buddy. It was a small sector shaft box. My new arm would not fit it. I personally went to a salvage yard and pulled one off of a 73+ duster. Both shafts were measured and the one pulled off the duster was bigger. They were kind enough to swap manual boxes with me. It's on my 74 duster now with new pitman arm. Is it possible yours could be small sector? Possibly I suppose. The link shared shows a difference in the top covers of the large and small sector boxes. Mine shares the same top cover as the small sector box.
