Benjamin 3120 Help

[SnoValley]

I picked up a Benjamin 3120 the other day (serial T224916 1975 I believe) and although it is in pretty nice shape it is missing the tubular magazine that fits on top of the barrel. Did a Google and was unable to find a picture of the magazine by itself or how it was attached to the gun. I gather it's just a long tube sized to hold the 22 cal round balls this baby shoots. If anyone who has one of these would be willing to pop a few pictures of the magazine details, it would be greatly appreciated. I'm pretty sure I could fab one up if I had some visual guidance. I would like to get this old repeater going again. It pumps up and holds and feels strong. Need to order some round balls from PA I guess, unless someone has a few they are not using   
Thanks
David