First time Dax owner

Hi all, I usually only mess around with Z50's but Ive just purchased two St70's (dax).
I haven't taken delivery of the bikes yet.
I'm woundering if anyone can tell me what year the following chassis number is from::

ST70-144447.
Thanks in advance

My guess would be 1970.

My ST is 139272 and has been verified as 1972/73.I've compared it with others with frame numbers in that "numerical" area-just a few hundred along the production line and shown in their original documentation so I reckon yours could be 72 or 73.
Hope this helps, Brian