Well the ones I bought are the part numbers that are listed on the Brodak site for the Bi-Slob. I didnt want to reinvent the wheel. Sullivan and Dubro clunk tanks go from 2oz to 4oz and skip that nice 3 ounce size that I would prefer. Hence going this route to the Brodak recommended tank. The other thought was the way everyone flies these things and fuel delivery. I wanted something that I wouldnt fight starvation issues. At this point I'll check out all the old tanks I have and see what fits but I may end up just building one. The Brodak tank just has standard venting and isnt anything fancy like a Uniflow tank.
Mark