I talked to a representative at Rustoleum and was quite impressed with their products. They have a rusty metal primer and a rust restorer that gives you a good primed based on so-so surfaces with traces of rust.
1. I used a wire brush on a drill to get rid of the large rust deposits. I also had a grinder but that was far more than I needed.
2. Then got a small wire wheel on a dremel tool, which did a remarkable job in all the tight spots.
3. Then I scrubbed the frame with a stripping pad from Home Depot and mineral spirits.
4. Wipe down with a rag and mineral spirits.
5. Review the entire areas and clean again with a Dremel tool where required.
6. Wipe with mineral spirits and clean with blasts of compressed air.
I am very happy with the results. Look at the photos of my bed replacement in process.
Bed replacement in process I'll have one coat of rusty metal primer, one coat of primer sealer and I am considering the Rustoleum Automotive
Matte finish for the top coat on the frame. They have quite an array of products and seem to be adapting to car and truck hobbyists for easy to use and effective products.