since we are guessing, there is a Turbotorch setup with tanks that has a J28 copy. The tanks are a waste, but the torch is nice. The torch is the SKH-7a, and here is a (warning PDF) link to the outfits: link
the torch is a little large and thus heavy, but it will work. You probably will want at least one different size tip. The one good thing is that used tips should be easily available once you figure out which Harris/Victor torch they copied. That's the only problem with J28 clones, for some reason used tips are rare and the new ones are $50 each. The Smith AW1A tips are half that.
I use a similar setup because I have to carry it around our cars to where I braze and then carry it back. If you don't have to do any carrying you will be much happier with larger tanks. Also,check with your local welding shop and see what they can do for you before you pull the trigger on this one. You might be surprised.
Thanks for the input, everyone. I'll keep looking around locally for other options - hopefully something is around.
The situation is basically this: My father has had a little hardware store-type oxy/MAPP setup for ages, and has always been annoyed with how quickly the little tanks get used up. He'd be getting this for his own purposes, and so the smaller tanks are handy for him because they're not much less portable than the little guys, but they should last significantly longer. I'd be using it because it would give more punch than my little MAPP/air torch, and having something available to use for free is always nice. So I'll see if I can put in some suggestions, but at the end of the day it's not my money, and I should probably be glad to have access to something workable.
I started out trying the little oxy/mapp setup. You're right, the tanks run out fast. The OA rig you get will be much nicer, regardless of tank size. You will be able to see how much you have in the tanks now so no surprises halfway through a preheat. The flame is better too. Not as small and intense. I think both run at about the same temperature but the OA flame is easier to work with.
I have had trouble getting enough heat out of MAPP to do easier joining tasks than that. However, people report building bikes with MAPP. Apparently if you are really patient and heat for a long time, you can get frame parts up to silver brazing temperatures with MAPP. The problem would be keeping enough flux around for the brazing operation. You should use a 45% silver so that it will build.