Where to find replacement tube, for my float tube

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I have a Float Tube that is about 15 years old and I need to replace tube. The manufacturer use a tire tube instead of a bladder that was built for the tube. I use a small pump that plugs into my cigarette lighter to fill the tube, this takes about 10 minutes. I blew the tube up last summer by not paying attention to the pump and the amount of air going into the tube while I was patching my waders. The cover is in great shape and I'd like to get a new tube or bladder for it but not sure where to look, I was wondering if anyone might know where I could find this. I goggled the only identifying marks on the tube (stillwater fishing systems) and best I can tell the manufacturer of my tube change owner ship and my tube is so long out of production they don't offer any replacement parts. The only identifying marks on the tube is "Stillwater Fishing Systems". I have included a couple of pictures of the tube. Thanks in advance for any help you might be able to give me.
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