Is a 2002 Ford Explorer engine interchangeable with a 2004 Mountaineer engine?

Here are a couple sites you can compare, read up on the Explorer and Mountaineer engines; I will put one link in a separate box to make it easy to hyperlink http://www.explorerforum.com/ntrprize/spec2002.htm

http://www.underhoodservice.com/tech-feature-exploring-ford-4-0-4-6l-suv-engines/

Thank you for that, but I am not looking into doing myself. Rather, A mechanic put a 2004 Mountaineer engine in my mom's 2002 Ford Explorer. Over a month's time, she received weekly calls from the mechanic telling her she would need a new part. We decided to get a 2nd opinion. The vehicle is now parked at a new mechanic's garage who claims that the 2004 Mountaineer engine is not interchangeable with a 4.6 2002 Explorer? I need to find out if this true

The Explorer is 4.0. or 4.6 and Mountaineer is 4.6 FFV. Best I could find The part the mechanic is talking about is probably the PCM..I would guess, they are different on the two ..However the major changes, according to that lower site didn't occur until 2006. But I can't think of any reason the mechanic would not just finish and get paid, if he didn't know what he id talking about

Thank you so much for your help...the original mechanic did not tell us anything about the the new engine except that it was "newer". Not that it would be more costly and need more components! I'll bet he didn't come here first to find out! :) it makes perfect sense.Thanks again!

Can I use a mustang 4.6 motor in my 2002 Ford explorer Eddy Bower 4.6

Is a 4.0 transmission interchangeable with 4.6 transmission both from 02 explorer?