coarse thread vs. fine thread strut rods

Correct, 67-72 have a fine thread and the 73+ style have a course thread. Also, because of the difference in the bushings the 73+ strut rods are physically longer than the early ones (to account for the thicker bushings). So, you can't mix and match strut rod bushings without compromising your suspension geometry. Not all of the aftermarket bushings are right either. Just one of the reasons I use adjustable strut rods instead of stockers.