don't get me wrong, if you're set on replacing it, go right ahead. :thumbsup: I'm just saying that with the 4.0: blow-by is normally an easy fix, oil leaks are usually an easy fix, and rod knock is usually just another noise. if it makes good power, then I'd run it. :D the 4.0 in my 88 has been starved of oil twice, overheated severely twice, has horrible blow-by, lifter tick and other noises, dirties the oil so fast it needs to be changed inside of 3k, had 200k+ miles and then I drove from MI to Utah and back to go wheeling. :yes: they just aren't like most engines out there. they are tough ol' buggers.