Can't give you a time line of this date to that date. I bought one in the late 80's new. If you are wanting a long one gunbroker has the barrels and complete guns a lot of times. There were also 30 and 32" barrels. The 38 makes a super quiet shotgun. If you are trying to date one. I would say I picked mine up in 87 or 88.
Marlin had a 120 before that available with a 38 or 40.