This Bring A Trailer shows a Kirkham with a KMP tag pic
https://bringatrailer.com/listing/20...7-s-c-cobra-2/
This one says KMS (no tag photo, from descr)
https://bringatrailer.com/listing/1965-shelby-cobra-75/
This one has a totally different number - KC9JSLC0656
https://bringatrailer.com/listing/19...am-427-kms-sc/
Another different one - KC14ESLC0786
https://bringatrailer.com/listing/or...cobra-replica/
KC13KNRC0766
https://bringatrailer.com/listing/20...oadster-427sc/
KMP235. Also has a photo of a page from the registry with lots of KMPs.
https://bringatrailer.com/listing/20...427-s-c-cobra/
KMP 174
https://bringatrailer.com/listing/1965-ac-cobra-7/
So there are both KMP and KMS, with some that aren't either. Probably has to do with when they were made.