what seam sealer?

Why don't you clean the rust off, and paint it with epoxy primer,??. That would be the best rust protection. You can grind it off, or sand it off, or sand blast it off.
That is what I would do.

As far as seem sealer I would use "Lord Fusor" 803. It's tuff and sticks to any thing, and you can paint it in 10-30 mins.

Just my .02

barracudadave67

I need something that can brush on. I cant paint with air in the garage. i dont have a cover and dont wont to take the chance of getting over spray on my dart sitting next to it. I will be wire wheeling the entire floor till its down to bare metal. all the old sealer just flaked off. under all the old sealer there is surface rust.