You live in the rust belt like I do, and Toyota trucks don't like it.
You can fix by grinding and welding on some plates.
But before I bought it I'd go over every square inch of the frame with a small hammer looking for more rust holes. Toy frames rust from the inside out, so by the time you can see it, it's bad.
Check especially where the frame turns upward from the horizontal (like where you found this one), at the body mounts, and where the fuel tank sits against the frame.
If the frame has more bad spots, you may end up in the constant repair mode, fixing new spots that reveal themselves after wheeling. This happened to me, and I eventually had to put a new frame under my p/u. Not fun at all.