I found a little bit of this (which I'm glad for - better to know better how things look now than to have a failure later) when I tore into the passenger side torque box. The lower side on it was pretty rotten so I cut away close t 75 percent of it, and exposed more of the rear portion of the frame rail.
Doing this showed me that the frame had some spots where it was in need of some additional work.
Here's me and Brynn. Based on the timing of this shot, I'm likely just realizing the extra work I've got in front of me.
I had originally tried to use some of my rust eating gel to dig in and get some of the heavier rust out. For some reason it's not a 'gel' anymore. Go figure. So some heavier grindign was required.
The top picture shows my patch - not the best weld in the world, but considering I was going from a 12 gauge sheet to a 14 gauge sheet, on the vertical, after really not welding anyting for well over a year I'll take it. Especially when its hidden behind the torque box.
The other neat fact. The patch was stainless steel left over from a tig welding class @ DMACC. There's also a piece in the bottom of the frame that needs replacing as well.I'm not dead set on how big the patch will be yet.
Looking at the bottom of the two pictures you can see how large the original stainless patch piece was. I made several passess trying to get my penetration right, grinding down any poor looking welds.