Totally agree a number of cars got the OTC tach as replacements for failed (and stolen) originals, my 66 has one, dated June 67, and documented by the original owner. Just pointing out the earliest example I have seen of that OTC style has a May 66 date. I guess it could be a restamp but assuming for the sake of discussion it is legit...could that style have been installed at SA on very late cars that were completed after May 66? If the difference was just a manufacturing production change would SA really care or just installed what was available? Not trying to rock the boat, just make sense of what I have seen...