This is somewhat a word of advice and vent of frustration.
I ordered 8 plugs to to do my V6 Ficht thinking I would be able to move them around and get them all indexed properly. Nope, four are all where they should be but I still have two cylinders where the plugs won't work.
I guess if you figure you have a 50/50 chance of them working then you should order atleast twice as many as you need and keep your fingers crossed.
All I can do now is order another box of four and hope they'll work.
byw ... here's a link with good instructions, that is if you hanvn't already seen it:
http://www.boatsetup.com/PlgIndex.pdf
I bought mine from Shipstore.com, best price I could find, plus they're only across town for me (Kansas City) so I get them the next day.