ID this steering linkage please

After doing some research it seems you are right. I was under the impression that the steering linkage I have was original to the car (72) as the K frame is original (biscuit mount not spool).

But heres the thing...

73+ p/s gear boxes should have the large sector shaft correct? Well it seems that both pitman arms actually fit on my gear box. So I have a 73+ pitman arm that is the same diameter of the earlier pitman arm???