Hi guys.
I'm looking at prolonging and protecting the life of the truck and the chassis.

I know there are various seals/products available for this purpose but I've not done a vehicle like this before.

I was wondering what products and what method you used?

How did you clean the surface rust off?
Did you get inside the chassis rails?
How do you get above the exhaust etc?

Any and all advice is appreciated.

Thanks guys.

I've not done my L200 but I plan on doing it before long. Before I do it I'll be replacing brake pipes, so the new ones are sealed instead of sealing corrosion into old ones. And I want to fit a body lift eventually so I'll do that before the underseal - so I get sealant on top of the chassis rails easier

When I did my 110, I cleaned it off with wire brush, wire brush drill bits and wire grinding bits then rubbed it over with Xylene (degreaser). I dont know if its because I did a half arsed job of it, or its a poor product, or because I had a massive diesel leak that reacted with a lot of it, but it didnt last that long, was rust showing through in places after about 18 months. It did see a lot of offroad use and not a lot of cleaning too

L200 I plan on doing all the sanding/brushing, then steam cleaning, then using either Fertan or dilute phosphoric acid which apparently does the same job - reacts with Iron oxide ie rust to make a stable compound (iron phosphate?). I might even put a few coats of primer or black hammerite before the undersealing too this time round

On the Landy I used Hammerite Underbody Seal in Schutz cans and the gun had a flexible bit on the end, got that into the holes along the chassis to get as much as I could inside, Ill probably do the same next time. Same around the exhaust, gearbox etc, just get as much on as you can. Mask off around the sills so you can get right up to the edges. I covered the gearbox, propshafts, axles, underneath the body, inner wheel arches, springs, trailing arms, track rod, you name it. No point messing about once your under it is there.

It's a shitty job but well worth doing. I reckon I could have put that one days work in and sold the Landy at £500 profit just from having a clean black underbelly

I used a hot jet wash to get the thick off.
Used a wire cup brush in a cordless to get the loose flaky rust off.
I run mine on ramps and do rear first then the front.
I always use Clear Waxoyl as i dont like the black underseal stuff, i use an Oil spray gun 100psi compressor(yes messy but you can remove the chassis grommets and fire it inside)
3 of 4 thick coats job done (had 3 l200s and done it to all of them).
Will be doing my new SUV in the next few months