The solenoid is integral to the starter. Really, though, like Jeff says, once you have it apart it will all make sense. However, everything IN the solenoid is available, meaning the contacts and the plunger. So why change the solenoid, even if you could?
Be observant of how things came apart, and reassemble identically. You probably knew that, but it is easy to discover a rubber o-ring on your bench right after you get it all back together. DAMHIK.
FWIW, I have never had to replace the plunger. They were certainly pitted, but they wear evenly because they rotate, I guess. I have dressed them lightly with a file on occasion.
Heb Dduw, heb ddim; Duw a digon
I'm that gun-totin', farm-raised, evangelical, pro-environment, OHV ridin'/drivin', Southern civil rights pro-labor Liberal yo' momma told you couldn't possibly exist.