one thing id like to add.
i recenetly bought a 4age headgasket through a local engine shop and they had 2 different part numbers for them. one for "early" and one for "late"
i assume it was bigport and smallport but yer there was definatly 2 seperate part numbers availablue. i think the brand i ended up getting was "durapro".
i ended up saying early model, cause its a bigport, and no problems so far.