Hi RED FIVE I have read your post below, this does not answer your question but roughly when they were changed, like you why change them.
(Note the 'factory fitted' sports mirrors, as confirmed by the build sheet I gave up with the car. For the life of me I can't understand why a Corvette specialist would replace them with standard types.)
What is making you think a Corvette specialist changed them, possibly the owner from 2008/2010 preferred the chrome mirrors, I quite like them and being taller I would expect a better rear view.
I would be interested to know if the chrome mirrors used all the old door holes, and also what about the door panels with the mirror adjusting hardware.
I watched the video posted by Chevrolet and it looks as if the door panels may have been changed.
I could make some sense of the change if done when the decals were applied and if the car was painted, but the Dave R photo shows decals and still sports mirrors.
My first photo of John’s car posted 20/3/20 shows the sports mirrors.
Your first photo posted 21/3/20 shows your car without decals and sports mirrors.
JonnyC4 posted 23/3/20 photos from the 2010 Nationals showing the chrome mirrors and decals.
Dave R posted 9/5/20 a photo from there 2008 Independence Day event showing the sports mirrors and decals.