hi Terry apologies for not getting back sooner things have been pretty hectic. Here is a link for the tettra tanks from central hobbies:
http://www.centralhobbies.com/Fuel/fueltnk2.html
Now you have to keep in mind that bubbless tanks are bladders encased in a hard shell tank but they are not pressure bladders like the old pen bladder types. The bubbless require muffler pressure which is applied between the hard case and the bladder. I suspect that any of the half A type mufflers would not be sufficient.
I will post up some pics of disassembled bubbless in a few moments. Now there also is tandem type tanks which are essentially just like an ordinary muffler pressure single tank only plumbed in tandem. Perhaps you could use a slightly larger engine which uses a conventional muffler like some of the .09's out there. these would work with tandem tanks.
Also will post up some simple Pictures to illustrate the tandem plumbing and some of my successful cross country airplanes:
John
