J.C. Higgins Model 20

I recently purchased a J.C. Higgins Model 20 pump shotgun. A really great old pump gun, a friend of mines father hunted with one when I was a kid and he was a bird killing machine.
It has the power pac choke but only came with one{ the long range tube} I am looking for more. Anyone have any for sale or know where I can get some?[/b]