Remember, the "3" is not the day of the month, but rather a model number indicator!
1 = Jaguar
2 = Stratocaster
3 = Telecaster
4 = Jazzmaster
5 = Precision Bass
6 = Bass VI
7 = Jazz Bass
etc etc etc!
Funny about the '73 date stamp... yes, Fender was hilarious about that.
One of my favorite ones-- Fender put two-letter date stamps on the tube charts of their amps. There was one letter that denoted the year and another that denoted the month. For example, the "PK" code on this bandmaster means it was 1966 ("P") in November ("K").
Sometime late in 1965, they switched from black ink to green ink on these stamps for a short time. "O" was the letter code for 1965, "P" was the code for 1966.
I've never seen a January '66 amp with date code PA. BUT about half of the "January 1965" amps I've seen (OA code) have their stamp in green ink, and I've seen quite a few green "OB" codes, too.
What clearly happened is that the person in charge of stamping the tube charts forgot to change the year on the stamp for the first month and a half. So you have to kind of know that if the stamp is green, it's a 1966 amp even though the letter say it "should" be January or February 1965.
Making it even more difficult is that when they finally switched the year to be right, they switched back to black ink.
There's also a possibility there was more than one person stamping charts... one with a green ink pad and the other with black, and that we'll never truly know for sure whether a black "OA" or "OB" code tube chart was stamped in '65 or '66.