I got to wondering why every name American drum maker was implementing serial numbers for their drums  beginning the 60's, yet Camco did not. Even Fibes issued serial numbers.

A Modern Drummer article on serial numbers I found on line, makes a strong argument that it was the retailers that pushed for numbers for insurance and stocking purposes. It also alludes that Camco only started adding numbers under the reinforcement rings during the Chanute, Kansas years (1971-'73) when Kustom took ownership from John Rochon. Can anybody confirm this is so?

In any case, it's just another Camco quirk.