I think I have found the holy grail of pitman arms!
I have an early 70 power steering box in my 74. I think we all know, there are two sizes of output shafts for steering boxes, the early 70 - 72 has a smaller output shaft, while the later 73 and up have the larger output shaft.
Obviously each box requires a different pitman arm. The pitman arm for the early boxes seem to cost over 2x more then the arm for the later box and are tough to find.
So the X factor in all this is the manual boxes...the manual boxes for all years have the same size pitman arm...the smaller early size.
Now, if you look at listing for Pitman arms, in rock auto, all pitman arms for 70 - 72 cudas are in back order, but there are two available for the 73 - 74 cudas, one for power boxes (moog K7076 Inner Diameter of splines is 1.1) and one for manual boxes (moog K7075 Inner Diameter of splines is 1.004). Both are very similar in price.
I have both in my possession (don't ask) and can verify that the K7075 fits the early power box. Visually they look the same. So unless I am missing something, it looks like the K7075 pitman arm is the solution for those looking for a new pitman arm for the early small output shaft power box.
Jason