Here is an explanation direct from "Howattman", the resident Howatt expert:
Since the mid-60's, the Howatt numbering system has been as follows,
"The letter(s) in front of the serial number (if present) represent the model (for example, HH xxxx is a Howatt Hunter)
The first number indicates the last digit in the year of manufacture (HH 9xxx was a Howatt Hunter made in 1969, 1979, 1989, or 1999)
The next numbers indicate the chronological sequence of manufacture (HH 9123 was the 123rd Howatt Hunter made in model year 1969, 1979, 1989, or 1999)
Of course, all of this is useless unless you know the variations between the model years and their identifying characteristics."
Based on the characteristics of your bows, I would venture to guess they are early 80's versions.
Dave