The alternator died on my "93 4.0 coupe. I tested it and found bad diodes. After much searching, I finally found the correct replacement. It's a very easy fix (once you get it out of the car!) and much cheaper than a new alternator. There are many YouTube videos showing how to test and rebuild the alternator. Also, most parts stores will test your alternator for free.
Here's the part I used: https://www.maniacelectricmotors.com/77904017.html
This is for the Denso Alternator used in the 4.0 facelift models. PN DBC 6819