Could be a early 1973 ... Maybe ...
From CGOA ...
http://www.classicglastron.com/gl-identifying2.html"Boats that were manufactured from 1970 - 1973 carried a seven digit number. The fourth
number from left indicates the year of manufacture. "
In 1973, Glastron starting using letters (GLA...) in the Hull Numbers.
Prior to that, the early 70's were just seven numbers, with the fourth number from the left being the year
(4322414 would be 1972). Starting in 1973 we were required to use prefixes.
Using the prefix you can determine the location the boat was built. Then
the seven digit id number will follow. A single letter and 2 or 3 more numbers which will tell
you the year of manufacture. These procedures are in accordance with coast guard federal
regulations"
Note that from 1973 forward hull ID numbers were stamped into the rear of the boat. This was federally
required for all '73 and later boats. This is good because the number will always be there and easily read in most cases.