I have a 336 that I am trying to identify the model. The serial number indicates it was manufactured in 1982. It has a straight grip stock and 18" barrel, chambered in 30-30. I had thought this was a 336T, but all of the information I can find indicates the 336T had a 20" barrel. Did Marlin also make an 18" barreled version? Any help is appreciated. Thanks.