Those who know Jimny's, know that they can rust like mad. I bought mine knowing it needed some work doing, but step one was to get it under-sealed to stop the rot for as long as possible, giving me a chance to work on it over the coming months.
I arranged for it to go to Rust Master in Hatfield, who coated the underside and injected the cavities with Waxoyl Professional. The process took about five hours. They provide a 5 year guarantee, and will also top up for free. This is good, because I know its going to need some welding so once this is done, I will take it back to get re-treated.
Here are some shots of the car after it had been treated (the shocks have been masked up, so cant be seen in these photos).