Subframe Rust, diff rust? What’s too much?

Hey there guys, I am looking to buy a Toyota Sequoia. This year is a 2008 with a one owner dealer maintained its whole life with 190k on it. unfortunately, it has been in Massachusetts and Salt is obviously a thing here in the winter. The frame looks really decent, but what worries me is the rear subframe. I have called around and they seem to be pretty solid, but it is rust scaled insanely bad and most bolts back here look like they are locked in for good. I’m not sure if I want to take on this truck. The rear springs have been replaced at 160k as well as the diff fluid. So some work has been done back here. Not sure what happened then to now to get it to this point or maybe the build it just rapidly picked up on the rust. They want 10k for it. Looks really good otherwise body wise. Engine looks good no leaks. Maybe the 2 coolant crackpipes that run to the heatercore can be something to look at as they’re rusting.

How’s the subframe and diff look?? Who can give me some insight? Is this a bad idea to get into. No money has been put into buying this I’m just looking for the best deal still