I don't have a 98 XJ FSM and the 99 FSM shows two connectors for the diesel PCM. Here's a link for the wiring section of the 97 in my google drive.
Hopefully there aren't too many changes between the model years.
The 60 pin diesel PCM connector is on page 8W-80-71 (page 383 of 472).
https://drive.google.com/file/d/1oln...ew?usp=sharing