Well, I had some of my extra YJ rims chem stripped and this process really cleans up the visibilty of the the codes on the rim bands.
However, month and date codes are not consistent as it seems when they were at KH being date stamped.
Letters and numbers can be found, and can be random.
I think either is correct.
Checking date codes at the valve stems, codes in the center of the rim, to codes in the band will help somewhat in ID'ing these.
Here are a few pics from a set I am selling :