I am wodering if a 1998 Merc sable has the same engine as a 2002. Or did mfg change the specs between teh model years?

If they are the same would it be easy to pull the 1998 motor and put it in the 2002?
Anything we should look for prior to buying the scrapped car- for just the motor? Iknew the prev owner, before he has a small crash- it still ran, but just wasn't road worthy.