Starrider88,
It's hard to say about condition of floor. The rust along the floor on your truck is probably localized. It hard to say for sure without being able to see it. If your cab mounts are still solid on this truck, I would say that the floor is too.
As far as undersides of your hood, fenders and so on, it hard to say which product is best. It really depends on what you want to top coat it with. I've used Rust-O-leum on my inner fenders then I like to use a brush on type of undercoating. Seem to last much better than spray can undercoating. One tip I'll pass along it is better to use the Rust-O-leum in the pints/quarts than the spray cans, seems to give a lot better results. Rust-O-leum can't be used under regular automotive paints thou.
As far as Zero-Rust, I,ve never used it myself so I can't say how well it works. They have a website with all sorts of info on their product,
www.zerorust.com .
If you have rust on your undersides of fenders and decide to use Rust-O-leum, I like to add just a bit of a product called Penitrol (spelling may be off), it an additive that makes the paint smooth out better and if you have pitted rust you can put it on in a wet coat, let dry overnite then prime with Rust-O-leum. Seem to work on rust real well.
