Confused about spark plugs for '99 3.8L

I have read many of the spark plug threads, but I am still confused. Do I need double platinum, single platinum, iridium, or what? Does anyone have a Motorcraft or Autolite part number? What is positive and negative firing cylinders? I have a '99 WS with the 3.8L.

Also, how do the ignition wires terminate at the coil pack? Thanks!

Can anyone recommend a good on line supplier or should I go to the dealer?

APP765 Autolite double platium is what I use the part number should be the same on a 99. I have a 2001. They look just like motorcraft plugs I think they make them for Ford. Do not get they double prong plugs I use those in my maibu
and had some multi fire codes come up every now and then. I have been told if I change them back to single prong plug, should stop that problem.

I have read many of the spark plug threads, but I am still confused. Do I need double platinum, single platinum, iridium, or what? Does anyone have a Motorcraft or Autolite part number? What is positive and negative firing cylinders? I have a '99 WS with the 3.8L.

Also, how do the ignition wires terminate at the coil pack? Thanks!

Can anyone recommend a good on line supplier or should I go to the dealer?

You need double platinum plugs. Double does not mean two ground electrodes (such as Bosch Platinum 2s) but rather it means platinum on both the centre electrode and the ground electrode.

I don't know the Ford part number but 99 Windstar and the engine displacement should be all that your friendly Ford dealer needs to get you the correct parts.

I went with the APP 765's and all is well. It took about an hour to change the 3 rear plugs. I am all cut up now. Ugh. Thanks for the help.