Jim: Thanks for posting the very interesting video explaining how the "AR" parts prefixes originated. If I got this right, when any Model A part that was superseded with a new and improved part, the old part was given the part number suffix "AR" in front of the original part number. Correct?
Therefore, any part that was superseded with a new part could have the "AR" prefix all the way to the end of 1929.
Also, calling any early Model A an "AR" is technically meaningless.
I never knew this and appreciate the information.