My Jeep CJ-X Project: Battery box and driver's fender repair, day one

This is what I started with. The original battery box on the driver's side was lumpy, a bit undersized for what I plan on putting in there, and riddled with holes. In my quest not just to piece the rig together but also to improve it where I can, I found a good replacement battery box (skeleton) to pop in place of this thing.

The replacement. A little too aerated than it will be when finalized, but it's crisp, true, and properly sized.

Cutting out the old one was easy.

Side by side comparison. Note the size difference.

The original hole. Since the new one is larger, I'll be able to get rid of some of this junk.

A sharpie line shows what will get cut off.

A little neater. More to cut off, though.

Crisper edges, but a little too small to accommodate the new box.

Just about right.

Here's a closeup of the hat channel that runs below the battery box. It's caked in some kind of primordial mud, and obviously it has rotted out the sheet metal panel.

I've picked out to see how far down it goes.

I've gotten most of the mud/crud out. It's down there on my workbench.

There was some actual wood left, but not a lot.

Test-fitting the new box. What an improvement.

I ground through as much of the paint and primer as I could to get clean metal for my welds.

Time to weld it in. Again, lots of holes right now that will be patched later.

Boogers.

There was a little larger gap than I wanted (about 3/16"), but I've got a plan that will not just fix the gap but also make the structure stronger.

Here's a shot of the first "patch" panel in place. I'm basically going to line the entire box. One might ask, then why bother buying a box in the first place? Well, it was inexpensive (like $20), square/true, and effective in design. By putting in all these panels to fill the holes, I'm going to make it even more solid for today's modern and quite heavy batteries (which I'll need for the V8).