Ed went through pictures and found the "70" style being used
at Dearborn as early as 0F102517 - Aug 69
at San Jose as early as 0R116735 - Sept 69
Didn't have any clear pictures of coupes or convertibles built prior to those two examples so can't report on cars built in the first few weeks at either plant. Don't see what 69 style could not be used - just don't have any examples or data supporting that nor do I have stamping dates from either of the trunk lids listed above