I'm going to be the first to say that is NOT just a patch job. That is a structural portion of the frame. You better be damn sure you get everything out of there. I would not want to be driving on that with just a patch job. I have rust on mine, and have even done some frame repair. If I were going to do that I'd remove everything, cut off the LCA mounts, remove the frame, weld in new frame, and weld on new parts.
Thats sounds like the best route when I call around tomorrow I'll mention that to see what some welding shops around here think wish me luck
Whichever way do decide to go...either a patch job or complete replacement...once you have it repaired you need to take some time and love on your 4Runner. You need to put some quality time on preventive maintenance or you're going to lose the rust war!! Get under your rig and sand off all that rust. Once you sanded it down...paint it with some POR or other type of rust inhibitor. It sucks...I know!! Been there...done that!! But you have to do it. Unless you have more money than time...then I guess you could pay someone?? I just took about an hour or so each weekend and broke it down into sections. Sanded down an area and then painted it with POR15. Before I knew it...I was done. Now, in the fall, I'll take a day and check the undercarriage. Places that have been hit with rocks or whatever...I'll clean it up and re-paint it. Doesn't take long at all now.
Hey, one more tip...don't forget our frames are hollow...with numerous holes. Make sure you spray your paint/coating inside the frame also. Otherwise you'll just rust from the inside out.
I hope this helps you. Have FUN my friend
- Russel