Got this response today from MichelIn:
Thank you for your email.
According to the Dot you provided this tire was built in 1969.
It is our goal to ensure that your issue has been resolved or your question
answered to your satisfaction. If we can assist you further, please respond
to this email or call us at 1-877-458-5878 (toll free) between 8:00AM and
8:00PM Eastern Time Monday through Friday or between 8:30AM and 4:30PM
Eastern Time on Saturday.
Sincerely,
Shirley
Uniroyal Tires
Consumer Care Department
No month associated with it

. '69 manufacturing date for my tire would be consistent with what I was told: i.e came out of a '70 W-31 built in the 3rd week of January.