Trying to find an engine for my 97 and I found a 2000 but I have a feeling that sensors probably changed in that time and I need to know if the wiring harness changed and the ecu.

 

Welcome to the forum

Yes, there were a few changes, big one was the fuel system, 1997 has 2 fuel lines, 1998-2000 just 1 fuel line, at engine

But when you swap any engine you usually just use the block and heads from the "new" engine, called the Long Block swap, you bolt on all YOUR old engine parts to the "new" engine, so everything matches up
So you will use your lower and upper intakes where the wiring, and in this case the injectors and fuel lines connect, on the "new" engine, so no changes, plug and play

2000 engine will have a 8 bolt flange on the rear for flywheel/flexplate
1997 "should" also have same 8 bolt crank, but if it was an early 1997 if may have a 6 bolt, if so you will need to get a new 8 bolt flywheel or flex plate, not a big deal just a heads up
Flange design was changed 1996/1997

I would change the rear main seal while engine is out, its a cheap part but hard to get at if it starts to leak

 

I didn't know that you could swap the engines out like this. Will the heads swap? What do you run into if you do this and how late a model engine can I swap into my 1997 4.0L truck?

 

Welcome to the forum

No, if you are asking to swap a 4.0l SOHC into a 4.0l OHV vehicle
1990-2000 Rangers had the 4.0l OHV engine
2001-2011 Rangers had the 4.0l SOHC engine
Only things they have in common is the displacement and trans/bellhousing bolt pattern
No parts are interchangeable

Original poster was swapping 1997 and 2000 which are BOTH 4.0l OHV engines