JOHNNY
I do not know if you can date a DAMON HOWATT by it's serial number. However, I can tell you that Martin took over Damon Howatt I think the early '70's. after that, they were the MARTIN HUNTER. So, If your bow says DAMON HOWATT, it is about 30 years old, if I am correct. Your best bet is to contact Martin Archery. They have all the records from the DAMON HOWATT Co.
http://www.martinarchery.com/ Customer Service 509-529-2554
For what it is worth, I have a couple of DAMON HOWATT HUNTERS. If they are in sound shape and shootable, they are great bows, regardless of the age. If they are in such a condition that they LOOK like they are only 3 yrs old, that is fantastic for a 30 yr old bow. As far as shooting quality goes, I will put them up against any of the newer high dollar custom bows being made today. In great condition, I would say they are worth about $200.00. You can check on eBAY COMPLETED ITEMS and see what other DAMON HOWATT HUNTERS are selling for.
Good Luck