welding up heater boxes

Does anyone have a suggestion for someone who ca weld up HE shells? Mine have some gaps around where it attaches to the exhaust. I'm trying to maximize my heat

Let me know how it goes if you get it done. I've got some that could use it, but I never have tried cause that metal looks soooo thin.

I welded the tabs back on mine. I also patched some hole where they ripped off.