Aside the 73 and lates 4 keys feature on the pitman arms is there another difference between these pieces? geometry ?
why the iddler arm would change too ?
I can see a PN change on these parts between pre 72 and post 73
The center link changed 73-76. The 73-76 center links take pitman arm
and idler arm that attach from on top.
Also the 73-up power steering boxes are larger spline diameter. So that pitman changed the spline diameter and it mounts from the top.
The over all geometry is the same 67-76. So you can swap certain groups of parts as a unit.
In my 68 Barracuda, I swapped to a large spline power steering box because is was the only style Mopar sold remanufactured. So I had to swap to a 73-76 centerlink (top mount), large spline pitman (top mount), and idler (top mount). Later, I swapped my K-member to 73-76 style. Also at that time I swapped my lower control arm, strut rods, and sway bar to the 73-76 style.