I think it looks like alot of rust, but what do other cars in your area that are 13 years old, with that manymiles look like? that could just be normal for your area. but I think that it looks like a headache if you plan on keeping the rig for a couple years. AND if you plan on wheeling it hard....yeah well i would be somethings would snap.
take it to a mechanic, or maybe a transmission shop, and ask their professional opinion - put it to them this way, "would you purchase this vehicle"
If it was me, I think I would pass....BUT I guess it also depends on how much they wanted for it. This all goes out the window if the thing only costs $500, then everything changes
hope that this was able to help, a little
best of luck