I just finished the repair on the gasatank on my "22". The small tank had rusted through to the outside and into the main tank. I cut the back out of the small tank (with a Saws-all) and cut the bottom out to the weld and up to the mounts on the ends. I sand blasted the tank inside and outside then cut the small tank out with a torche. Made a round plate to plug the round hole in the rear face of the tank and welded it in place (mig weld) Than made a new bottom from 14ga steel and rounded the end's to fit the hole I had cut in the bottom. I saved the gas fitting from the old bottom and fit and welded it in to the new piece for the bottom. With a little grinding and sanding and a coat of primer it looks like a new tank. Well almost, the flat plate welded in where the filler neck use to be looks different. I have ordered a gastank sealer kit from POR 15 ($28.00) www.por15.com So will slosh the tank when the kit arives. Hope to end the fuel tank leaks on this old Cat. Total cost about $50.00 bucks for parts and lots of labor.
Just thought you may be interested.
Frank