Pitman Arm Compatibility

So if I match the arm I require with the steering box, the rest shouldn't matter?

No. The pitman must of course match the box because of the spline size.

But the FOUR PARTS all must match

That is the early / late linkage

so box must fit the pitman

Whichever way the stud points "up or down" on the pitman determines the center link and pitman

Look at the thread I posted. there are shots there right out of the shop manual