Interesting find on my Corvette tach.

[Kurt S]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ssl78</div><div class="ubbcode-body">I would think that they had to pull a tach off the line at certain intervals to test accuracy thats what happened and the guy who did it had to sign and date it. </div></div>
Not off the assembly line. Maybe audited in the supplier plant, but it wouldn't be signed.
This is a later repair or calibrate job.