Wheel date code. Tell me if I am reading this correctly??

BB-Dave said

M6.....is Motor wheel plant #6,
9.......is for 1969

should be a number to the left of the valve stem (day of the month)
then the 3 is for 3rd month(March)
5.5" wide

These were made in March of '69

Dave

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So am understanding this correct? M5 is the plant, the 9 under the M5 is the year of manufacture, what is the 6 to the left of the valve stem and the 3 to the right? The 5.5 is the wheel size. Is it 6/3/69? Or is it 3/6/69?
Joe