In late 1986, Toyota changed the body plate to rust-proof steel. Therefore, it is said in Japan that later models are resistant to rust. It still rusts, but is generally said to be better than earlier models.
The 60 series is even tougher than the Hilux. Here in the Himalayas, I saw a land cruiser60 carrying 25 people on a harsh mountain road. Mine has exceeded 1 million kilometers and the engine has been overhauled 3 times, but the chassis has not been damaged at all.