If I'm not mistaken, the 30XX series were produced for OTASCO (Oklahoma Tire and Supply Company, or something like that).
They're basically a Glenfield Model 30, which in turn is basically a hardwood-stocked Marlin 336.
The last two digits of the model number indicate the year of distribution. I think they ran for about six years. Each year featured a different western-themed medallion in the stock--Pony Express, The Alamo, etc.
These were not high-end commemoratives; really more of a marketing strategy, I believe. I'm not aware of a real collector's market for them, but they turn up from time to time.
Someday I'll find a killer deal on a nice one and take it home with me...
According to Brophy's book, Moose_Maximus is correct. The medallion for this year (1979) was American Hunting Tradition. The serial number should start with OB. These guns were made for OTASCO for ten years from 1978 until 1987.