If I am not mistaken (this time), I don't remember any references to the tach on the build sheet. With all due respect to Mr.Gaines (genuflected when I said that), I HAVE seen 68 Shelbys with 6,000 rpm tachs, way, way, way in the past.
There is also something about some with "redlines" and others without?
This was a long, long time ago when I got yelled at to get a hair cut and my pants were too tight? Way before anyone was reproducing anything (except maybe kids). So long ago, I don't even recognize me in the pictures?
So my PREDICTION is that this will remain unsolved even though this thread may linger on for years?