Every Marlin has value, and the better the condition, the better the value. The 1970 commemoratives will generally bring a bit more than typical Marlins from that era, and especially if the original packaging was kept intact. If it's like new, without the box, it should bring $50-$75 more than a 1969 or 1971 std. model 39a.
Marlin lever actions 1870's-WWI, Ballards, and single shot rifles!