Re: 2001 3.0 to 2003 4.0
you'll need a tranny, entire engine/trans harness, pcm, exhaust, PATS reflash. And that's all without comparing the engine bay to ****pit big wiring connector.
Honestly...just 5.0 it. I wish I had. And I went 4.0 to 4.0.
'01 XLT disguised as a '03 Fx4 Level II.