doriangrey
There are numbers on the box, and I believe the code or serial nmuber on the box does identify the year, but I don't know how to translate the numbers to identify the year that the model was made.
No, there's no year code. "35" identifies the series and the rest is just a straight sequence number.
With the armour kits, there's often a Tamiya logo and the year that part was first tooled on the inside of the lower hull pan. That's not always a good indicator though, as that part may be utilised in later releases/variants of that vehicle.