Hello from another MA guy.
Nothing much to add to the general consensus - all good thoughts.
Now that the weather is cold I'd start by spraying just about any liquid oil on the rust to get good penetration, followed by the thicker product of your choice; FF, WoolWax, PB, etc (bought in bulk...
Funny, a friend was just thanking me for suggesting them to his wife before Christmas.
Love mine, both the pliers wrenches and cobras.
The pliers wrench really is the exception to "An adjustable wrench is, by definition, the wrong tool".
Somewhat more seriously than before ~ when weathered after brushing on Rust Bullet looks rather like hot-dipped galvanizing.
It doesn't seem incongruous for your sliders to look 'tougher' than the rest of the truck.
If you mean replace the brushes without pulling the alternator - no way.
Can't imagine even getting the rear cover off without removing the alternator.
Soak every connecting part with ATF/and or your favorite quality penetrating oil several times in the days leading up to the job ~...