Will it work?
The 4.0 was the same OHV engine in all applications until 1997 in explorers and then 2000 in other models when they switched to the SOHC
Do it.
Those are both pre-OBD as well, so I wouldn't think there would be any issues.
If you do this you need a few more things, the engine wiring harness and the computer from the donor vehicle, then it will be spot on. It also should work if you swap all the emission control stuff that is different from the old engine to the new one. If you mess up while doing option 2 it will be stuck in "open loop " mode and you will never ever get good mileage.
This happened to a friend of mine.





