yo Sam,
Since there is a gap, because the two are joined by spot welds @ the factory, I Guarantee there is some outstanding rust pockets inside; at the outer 1/4 panel's wheel well lip where it bends inward and up at the top of the wheel well inner housing.
We bought our 96 New and kept the lips clean; overtime we washed it (weekly by hand, even in winter) we cleaned the area well.
Up until last summer, we cleaned-up minor rust on lip that we fully believed was caused by stones; last summer when I decided to remove the wheel well moldings, yep! Hello Mr. Rust Holes.. Mr. Rust was laughing at me; he said he was hiding under the molding for years!
I got my Dremel out and lost about half of the lip on the passenger side... nearly all was gone around most of the blind rivets.
When I get patch panel someday, I'll use Body adhesive (& some blind rivets to hold the patches tight to the 1/4 panel skin at top and sides of the patched area) to attach em to the 1/4 panels instead of welding and spot welds.
GL
