Ford Exlporer

If they are GT 40 or P heads there will be a set of bars on the front and rear, III for GT-40s and IIII for GT-40ps

GT 40 heads will say GT on the corner of the casting, GT 40p heads will say GTP in the same spot.

GT-40p heads will require MAC or FRPP headers for GT 40 p heads

I have done the swap with MAC shorties, a couple of plugs are really a pain this way...

http://www.badassmustangs.com/forums/index.php/topic,6876.0.html

Everything you could want to know about GT 40 and P heads, or look for FreakingStang and TMoss on forums...