Well low n behold I just got an email from AMA.
No news as of yet but atleast they responded.
"Dear Jamie,
Thank you for your email. Membership number records are held in the membership department so I’m cc’ing our Membership Director, Shawn, on this email. He may be able to help you with your question. We are unable to give out names of current members at HQ, however this possibly could be a deceased member’s number. Please note there are some other caveats to the search. It is possible more than one person had that number. Within the first 20 or so years of AMA coming into being, numbers started being reassigned if a person did not renew their membership in time. Thus, there could have been multiple people with the number 6653 since the airplane you found was built. And, to add to the mix, we do not have membership number records prior to 1974, so if someone else had that number prior to 1974, we would not know who that was."
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