The rusty driveshafts drive me nuts too.
Easy solution. Put the truck on a lift, or up on jackstands. If it's 4wd, put it in 4x4. With wheels off the ground, and someone in the drivers seat, have them accelerate to 20-25mph to get the shafts spinning.
Take a steel bristle brush, and *carefully* work it up and down both drive shafts to remove the rust, while they are spinning. While still spinning, hose it down with brake cleaner, the spray paint with good rust resistant paint. Obviously, be careful as hell while you do this, including wearing eye pro so you don't end up with paint or brake cleaner in your face.
This method makes for a good, even coat of paint that will stick around for a couple of years and only takes about 10 bucks and 30 minutes. I do it to all of our trucks here.