When I get home I will check the barrel code and see. I don’t know right off hand.
Barrel code will only tell you when the barrel was Made for positive as it could have had the barrel changed.
Unless you have had the gun since new and know that it is original.
if the reciever is marked LT-20 and has a sculpted ejection port and long barrel extension then you know it was made after 1977
if you know the barrel is as it came from the factory then you know that it was made in 1986 or later as that is when the Rem choke system was introduced.
With the synthetic stock again assuming it has the original stock it was made in 1996 or later.
With Remington now defunct it is tough to pin the date down exactly.