I found 1975 guitar on Japanese searching site.
I contacted the shop, and I got some more info.
 
Serial No. 75-165
One owner
Included all original Power supply, Cable and Case
Offering price is over$10000
 
It seems like new condition from pictures.
I am interested very early power supply. It's called DS-5 or not ?
 


 
 


 
 


 
 


 
 


 
 
More pictures on the link.
http://www.musicoffice-t.com/alembic-ss.htm
 
Eiji

That is what the original power supplies looked like for the earlier instruments.  It is strictly stereo.  Although easily modified to be mono as I have done this to one myself.  
 
I am not sure when the blue box started, but I am guessing in 1975 from what I've seen.

Very nice!