William,
So if you go with that percentage though the end of production, that would roughly come out to about 360-370 Z/28s for 1969 ( total RPO N44s - 2161 x .17). And from what I've been reading it was not fun to drive so I wonder how many ended up in a ditch.
On a side note, have you, or anyone else, ever seen that part I have - 5678504 (or equivalent if part number was later updated)?