While replacing the fuel lines and installing sway bar I noticed that boxes in the gas tank area are filled with dirt and leafs . I'd like to clean up and rust proof that area once and for all. What is the purpose of those boxes, how critical are they structurally, has anybody removed them? Normally, I wouldn't think twice, cut the metal, clean the area and weld it back. However, in this case, it will be very uncomfortable to weld bending over the fender and looking upside down. What are my options? Can I devise some kind of bracketry to replace those boxes? Any ideas are greatly appreciated.
Thanks,
Mike

Torque box?

That is actually the unitbody chassis rail. It's a structual member.

To quote the founder of Faber College "Knowledge is good".

Thank you, Rick. I'm thinking of cutting it and welding tick angle steel on its place. My second option is to cut access panel, do the work and weld it back or make a cover plate just like front/rear tunnel.

Seems like a lot of work for something that doesn't look bad at all from your pics.

I just gave mine a good cleaning with a shop-vac, doused it in Metal-Ready and moved on.

Seems completely unnecessary to me.

I gotta agree with Andy and Gint. Lot of work for dirt and leaf removal. 120 psi air in one hole oughta blow everything out the other hole.

Thank you, guys for solid advice. You're right, that metal is in really good shape and it would be a shame to butcher it. I'll just blow out and vacuum as much crap as I can and leave it alone.

If your compelled to try to prevent any long term rust damage to the inside of the rail use a high pressure sprayer and blast the crap out of it. Use a blow gun with compressed air and blast it again. Once you know its dry (maybe with the aid of a heat gun) go to your local autobody supply store, get some brand of metal conditioner/rust converter and use rag swabs on the end of a twisted wire to wash what you can through the holes in the rail. Once you have completed the conversion as outlined on the instructions on the container or what ever brand product you used, break out the POR 15 and use the swab method to coat whatever exposed rust you can get to through the holes. Your autobody supply store should sell the swabs on a wire. you will need about a half dozen to finish the job. A 1/4" drain hole at the lowest point of the under body pan may help and water, rust converter and POR15 drain out.

I have a modified nozzle for my vacuum cleaner. It has a 3/4" dia. hose on it that fits into tight places like those that you're showing. It works great, but after about 15 min.s or so the vacuum cleaner overheats & temporarily shuts off. FYI. Whatever.

I recommend welding those anti-sway bar brackets in place.
To do it right requires opening up the box so you can weld all the way around the bottom of the triangular plate.
If you don't weld them securely, the inner fender will eventually spider-crack around the bolt holes.

Ditto. Doing it before they crack is the ticket. Mine cracked around the sway bar boss... all the way around it, but only on the right side. It wasn't hard to weld but took more time than if I'd anticipated it. You can schedule PM.

Excellent point, Chris, Thank you. I will open it up and weld in the sway bar plate. But can I leave it open or I must close it. If I have to close it, can I just make a cover plate or I have to weld it closed? I will cut along red lines.

the factory welded those plates on the outside and didnt cut into the frame rail

On my car, the stock sway bar mounting was just three nuts welded to the sheet-metal of the fender. Or at least that was how it looked. One of the welds failed while I was removing the bar, so I used a plain nut in place of the weld-nut. Fortunately, it was one of the upper ones that failed.

--DD

The three nuts were welded to a reinforcing plate which was then spot welded to the inner fender.

We cut the top of the box open, weld the reinforcing plate, then weld the top closed. It may be easier to make a new cover rather than re-using the piece you cut out.
The hole in the top of the box on the pass. side was for the washer bottle pressure hose from the spare tire.