John : I believe that I have solved this ?Mystery?.
We know that in 1967, the Rocker Panel Moldings were only available in Special Packages (like the Sprint Package) or as a separate stand alone Factory Option. For 1968, all Models, at least initially, came with Rocker Panel Moldings. The Rocker Panel Moldings were not offered either year as an Accessory Kit. So, if your 67 did not come with Rocker Panel Moldings from the Factory, one had to order both a right hand (C7ZZ-10176-A), and a left hand (C7ZZ-10177-A) Rocker Panel Molding ; luckily, both came with ?Attaching Parts?.
Ford must have thought that a lot of these were ordered in 1967 (more than just for replacements due t damage), and in late 1968, decided to offer a Kit for 1969. As this was designed (put together) in 1968, it, like many 1965-67 Accessories, carried a Part Number that reflected the year before an Accessory was actually introduced/ available.
Sure enough, the 1969 Accessory Catalog shows the C8ZZ-10146-A Kit (copies from 1968 Ford Accessory Catalog attached). Being in the 1969 Accessory Catalog, one must figure that this Kit is for 1969?s, not any other year. No Accessory Rocker Panel Moldeing Kit is shown in the 1970 Ford Accessory Catalog. Each the 1969 and 1970 Rocker Panel Moldings were unique to that year (C9ZZ, and D0ZZ, respectively).
As for the C8ZZ-10146-A appearing in an OSI Catalog, I went a little further than just your 1976 OSI. I looked in my 1967,68,69,70,71,72,74,76,77,79 and 814 OSI Catalogs ; no C8ZZ-10146-A is shown.
Not a real surprise as, over the years, I have found three different things appear when searching for an ?NR? (obsoleted) Part. Sometimes it?s never listed ; sometimes it?s only listed once, never to appear again ; and sometimes it?s listed each year for a 10 year period. Of course, I don?t have all of the OSI?s that were printed during the periods I listed, as some years, there were as many as 5 issues printed during the year.
Hope this helps,
Bob