Working with fuel tanks can be extremely hazardous! Only attempt such work if you know what you are doing, and at your own risk! Don't come to me if you kill yourself to death! You have been warned!
We filled the tank to the brim with water, to eliminate any chance of combustible vapor. Using a plasma cutter, I zipped the top of the tank off, to show how the inside of a B tank is constructed.
You can see on this original tank, the two baffles welded to the lower half of the tank, and the pickup tube on the right. The sending unit is frozen in place.