Soo…
The engine harness is 98% plug-n-play if you have an ideal donor. The big square plug, plugs right in. The small plug on the drivers side for the starting/charging harness does not. Have to splice wires or build an adapter (which I’ve done). It’s only a handful of wires and I even have a video about it on YouTube. If I had the extra parts I could even build an adapter harness for someone.
The bad is, a 98 Explorer is a not-so-ideal donor for a 98+ Ranger. Ford did some strange things, the 98 Explorer got PATS, but had the return fuel system with the lower fuel pressure, like the 97 and older Rangers. I’m not sure if things can be modified. I asked and was told no, it doesn’t work, but nobody was able to explain why. I ended up trading parts with someone who had what I needed to convert to a 2000 Explorer (computer, pats, ignition and keys, fuel injectors, fuel rail, engine harness, cam synchro).
Other problems I ran into with a 98 donor was for whatever reason, the driveshafts ended up too long by roughly an inch. For the front, the Explorer front shaft fit fine. For the rear, I have to cut down my driveshaft. I don’t know if it was something to do with my choice of donor or that I replaced my Ranger axles with the Explorer ones (they shouldn’t be different sizes).
The PATS module is buried in the dash, a white box. That and the ignition cylinder and keys do not have to be replaced. You can, and it simplifies the process because nothing needs programmed, but the first one I built, we didn’t know we needed that stuff so we ended up having a dealer reprogram the thing. The one I’m currently working on, I used Forscan on my laptop to program it and it was a pretty painless process. Little time consuming because of having to unlock the anti-theft (it’s a time-delay procedure), but once I was in, I just had to tell it that I replaced the computer and it did it’s magic and instantly all of my Ranger keys were fully functional. It was like I had never changed anything, no need to reprogram keys.