Rich,
The info provided from Pullrite indicates the Mor/ryde King Pin Box requires a 331707 Quick Connect Capture Plate for your SuperGlide 16k hitch.
Click/Read Quick Connect Capture Plate Sizing Chart
On that chart you will note at bottom left Mor/Ryde requires a 331707 Quick Plate to match your SuperGlide hitch.
To verify I also suggest you call Pullrite/SuperGlide at Mishawaka, IN for Linda Marie Groning at 800-443-2307 ext 111 and ask her directly what you believe to be correct number for the capture plate.
I hope this helps.