I think I figured out.. All of this may be common knowledge but after googling, asking questions and searching, I never really got a definitive answer. I did read that dodge used the same (mostly) manual steering box in A, B, E etc all the way to 76, never changing the sector size. So I started looking up part numbers and found that pre 73 used the same pitman arm on manual and PS boxes. See where this is going? That means that all manual pitman arms are small sector. So I'm pretty sure that I can just use a 73 manual pitman arm (plus everything else 73) on my small sector PS box.