The 67s had the stud-mounted idler arm. That is not a very good idea, and from 68 on, they never used it again. They are,however,all interchangeable from 67 to the end, in 75 or 76.And you can use late style arms(73up) AND C-link in the early K(72down), and vice versa.The key is that the arms must be ordered for the Centerlink;that is to say they are a matched set.. The inner tierod ends go with the C-link, the outers with the knuckle arms(lower BJs)
The 67 K could be modded to fit the 68 up idler arms, if you have the skillz.
The main difference between the early Ks and the later ones is the engine mounting system.
Very often the early arms will interfere with the header-tubes.
I have, on my 68; the 68 to 72 K-member, with the 73 up steering. The TTI headers had to be dinged for clearance to the steering arms, even using the late steering.
Many headers will not work with the fast arm(s). The arms will hit the tubes.
