The article seems accurate to the best of my understanding.
I noticed the spring perch date change-over date is sited as being in mid-November 1966, well into the 67 model year though the Title of the perches are "65 and 66" or "67 to 73".
Would it be splitting hairs to note the (estimated) changeover date in the titles?
BTW, my Nov. 2, 1966 carrys the early "MS" marked perches, originally tack welded, no crimp, early bushings with Rockford fine threaded bolts, exactly as described in the article. I did restore the bolts to phosphate and oil because I saw no signs they were zinc or cadmium...I may be in error on that detail.