Manual steering gearbox

I wasnt aware there was a difference when I bought my manual box. I was also told they were all the same. I ordered the correct pitman arm for my year car and it was for a larger diameter sector shaft. Went and found another manual box in a 73+ duster and it had the larger diameter shaft. I'm going to guess they aren't as common as the earlier. Seems most of the later model a bodys got power steering.