"also it was not 4 it was 6 with a tapered seat that must be properly cleaned lubed and torqed and rechecked. when so done they don't blow out. lazy and cheap on proper maintinance owners are the problem not the motor"

Wrong!!! There have been PLENTY of people on this board and especially over on NLOC who have documented that they only have 4 threads and the one hole in particular(I think it is the 3rd one back on the passenger's side) has been found to have only 3 threads by several people.

http://nloc.net/forum/showthread.php...k+plug+threads
http://nloc.net/forum/showthread.php...k+plug+threads

Lazy and cheap on proper maintenance??? I thought the Ford manual said these spark plugs were good for up to 100K miles. I looked all through their literature, manuals, etc, and I couldn't find one place that showed the maintenance interval on torquing and rechecking spark plugs. Hmmm....... It's a faulty design. Period! Why else would they change it in late '02????

" just go back to the old air cooled vw's they had a 3/8's plug and always blew them out. so has many old b&s lawn mower engines."

And in all that time since then, no engineer was able to overcome that challenge of too few threads allowing spark plugs to blow out, until October of '02 with introduction of the 10 thread modular heads. Amazing!!!!

Some people have been able to, potentially, avoid this problem by changing to an aftermarket plug and by rechecking them every 20K or so, but that doesn't change the fact that it IS a BAD design.