Sorry nobody has dropped by with an answer for you, this forum's been very quiet lately.
Dating APII guitars is always an adventure, but the serial number is the place to start.
Here's some general info from the Ariaguitars International web archive site. Looks like your guitar would be 1981:
Quote:
Dating Aria Guitars
Dating Aria guitars is a mix of fair precision and historical triangulation. The early guitars did not contain serial numbers, so you have to go by the rough historical outlines here.
There are no pot codes. In the mid-'70s serial numbers began to be used.
At least for Aria guitars made by Matsumoku, the serial number contains the year of manufacture in the first one or two digits (Y##### or YY####). Thus, a guitar from 1979 might begin with 79####. One from 1981 might begin with 1#####.
The scheme becomes less sure after 1987. Some Korean- made guitars use a serial number with year and week indicated in the first four digits (YYWW####). Thus 9628#### would be from the 28th week of 1996. However, this is not the case on all guitars, and some have serial numbers which are not date-coded.