Moose75,
Contact Remington or DU chapter for information on it's DU SER#. These were presentation shot guns{dinner guns}.
The most rare is the 1973 {dinner gun} only 600 mfg.
The 1981 DU LT20ga, and 12ga {dinner gun} 2400mfg ea.
The 1982 ATLANTIC FLYWAY {dinner gun} 2400mfg.
These Rem 1100 shotguns were produced for fund raisers.
To have rare value they have to be unfired, in box with warranty papers.
BY ser# they will tell you what year it was made, 1973,1981 or 1982.
Don't quess on how old it is, contact them. Let us know what you find out?

Hope this will help!