Well I played with three different media types, through the Harbor Freight Sand Blaster. It only works with very fine material reguardless of the head/nossle size. After multiple attempt to get it to work, I wasn't impressed at all with it. It was great for making a huge mess, but not very effective on removing rust or paint,even at 120psi, so it goes back today. I actually managed a bit of better cleanup on the body and under carraige with my pressure washer, and there is no mess to cleanup afterward! Also able to sell some old parts off the truck which is paying for the American Autowire wiring harness, so that worked out well.
Not too upset with the sandblaster trial, as it was an inexpensive investment and worth the try!
I still find the 3M sanding disks seem to work best on the surface rust!