The phrase 'the starter proper' is correct grammar for saying 'directly mounted to the starter'. I guess you missed English class the day they explained that, huh?
In all seriousness, the starter solenoid on a 97 does double duty. It engages the drive into the flywheel, and it also closes the main high-current connection to the starter windings. This is different than the older XJ's with the fender mounted Ford-type starter solenoid/relay.
I don't own an XJ any longer, but I still think they are the best of all the Jeep products ever made. My XJ was my favorite vehicle in my 50+ years of driving.
So...I stick around and give advice.