Taiwan FG Red label 180 date code question.

Hi I am trying to put a date on my Taiwan made fg 180. The serial number is t0013896 and the date code appears to be 60.6.21 From what I have been able to find the date code would indicate 71. Is this correct? I ask because on yamahavintagefg.com it says the earliest serial number/date code set they have found found is T0015094 & 60.7.1 (1971). Wouldn't this be earlier? Thank you in advance!