Later steering gear has 7/8 diameter thread which requires a 1&5/16 hex nut. The earlier steering gear has the same 3/4 diameter thread as the manual gear.
Anyway... the hex nut is the quickest identifier.
Well, I checked it as RedFish suggested above and the thread diameter is 7/8 so it a 73 post unit. Please correct me if I'm wrong here, so I need a post 73; Pitman, Idler, Centerlink, and 73 inner tie rods to work since I have all smaller 72 linkage in there now to make this post 73 Steering Gear function properly?