welding on the unibody

I have a 91 2dr with a rust problem on the rear passenger footwell. There is a hole just smaller then a dime above the muffler and there is a very brittle area about the size of a magazine around it, which gets worse the closer it gets to that hole. With a unibody and the flex involved, is this something that can be succesfully welded? I am considering whether to keep this one and upgrade it (stock 2.5, 206,000 miles) or get another one in the spring, and the rust problem is a determining factor.

Yes weld away. Best to cut out any area thats rusted with a grinder and butt weld in a peice of heavy sheet metal the exact size. If it were me and I was going to be in there anyway I'd cut out any rusty stuff, even if it's just surface rust.

I sounds like you haven't done much thin welding. The foot well is a good place to get some practice in. A few blow holes and some warpage can be easily hidden there.
In hidden places I like to cut my inlay a lot larger then the hole. This makes it easier to fit the peace. Then drill holes in the patch midway of the overlap. Fill in the holes with weld to the base medal as well as the edges and the patch can be stiffer and stronger then the original.

Thanks! My previous experience has been ladder frame Land Rovers, and even then I only did the re-wire and suspension, so I definatly do not have experience with thin welding and unibodies! Sounds like I can go for it, with a welders help of course!

the best way to test this out is to get a couple pieces of approx. the same gauge sheet metal and pratice your welds on that. that way you can get the temp and timing right so you dont go melting a hole through your floor. i plan on patching my floors soon doing exactly what was said before. cutting out a piece then welding a larger piece in an sealing it with silicone or whatever. the only way i would go at this is with mig or tig i wouldnt even btoher trying to stick it

If the rust is bad enough you can get a panel that is pre bent to fit http://www.shermanparts.com/page.php?c=shop&p=new_products&id=14

Stickwelding thin metal is not easy, MIG is much easier to do.

Do you plan on welding this yourself or having someone else do it?

Hey, I checked out that link for Sherman parts - looks great! Thanks for the info everyone.

This thread should also help you
http://www.naxja.org/forum/showthread.php?t=93552