Well, I am on the fence with this one. It could be a good truck, if what is being represented is true
I would want to see receipts and a maintenance history--don't call ahead for this, ask for it when you look in person. (don't give him time to falsify records.)
The GT40 manifold issue-well our intakes aren't "true gt40" but they are internally similar. He may have in fact installed a mustang's gt40 manifold onto it.
As for the p-head question, this is a designator for an external EGR system.
The non p heads have internal egr passages. They also flow a bit less than the "p" heads. P heads are on some late 97's and most early 98's
Now--didn't whaithere just score a '01 mounty with 72k for 5500?
A few things to check
when moving in reverse, and then forward again, listen for unusual clunkung sounds--do this a few times.
Listen under hood, while another revs engiine. listen for exhaust leaks, especially on the passenger side.
Late 98's -01's have cast manifolds with no heat shielding. Earlier models have a tubular style "header" which can crack.
when key is first switched on--watch for the Check engine light to illuminate, then go off when engine starts.
while driving on highway--accellerate to 70mph, let it level off to that speed, then notice tachometer. It should read approx 2200 rpms.
on a level or slightly uphill grade, at 28 mph--floor it. It should shift quickly to first gear.
Let us know what you find out---
start at 4000, work from there!!! 4k is no insult for a 9 year old truck!!