If you call marlin they can send you one. I have a marlin model 80DL myself. They are still producing rifles that accept the same magazines for these rifles. Or you can order them here: http://www.ammoclip.com/m/marlin_80,80c,80dl,80e.htm
They are only making 7-shot magazines with the red safety followers. They work great in my rifle. However, the rifle was advertised as an 8 shot rifle and the early, original magazines (probably from 1949) had no red safety follower and held 8 rounds. I have one of these magazines and I hold on to it with dear life as I never have seen nor heard of another in existence. I asked Marlin about such an 8 shot magazine and nobody there has ever heard of such a thing.