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4.0l OHV and 4.0l SOHC used the same Block so transmission bolts will match up, 4.0l SOHC has an extra bolt hole but doesn't need to be used

Also motor mounts are the same
Exhaust system needs to be changed, maybe just the manifolds but they may not match up with 1999 pipes

You will need to change computer and engine wiring harness
And the PATS(passive anti-theft system) system is in computer so you would need to change PATS keys, or have a mobile locksmith add your current keys to the new computer, this can only be done once computer is installed and wiring connected.
Computer also needs to Match Transmission in the 1999 Ranger, manual trans and automatics used different computers, 2WD or 4WD doesn't matter

2001 4.0l SOHC falls into the 1997-2003 window of timing chain issues, so I would plan on changing these while engine is out, also rear main seal, always
You could just inspect the two long timing chains and just replace the tensioners if the guides look OK.

 

This video helped me sooo much.


Changing the timing chain and tensioners...that's key for longevity. I wish I knew that about a year ago :(

You MIGHT be able to rent the timing tool from a specialty tool place, but I went and bought one off Amazon. Worked just fine.