I just got back from having mine done. It took the technician 8 hours to change 8 plugs. 3 of them broke off as mentioned above. I have never spent so much on having plugs replaced. To top it off, the actual plugs were $21 dollars a piece for the shop and then they have to charge a mark up. All in all it was over $450 just to replace some plugs..... What a bad design by ford. I thought I was going to get lucky since my truck only has 62k miles on it. To top it off, the "quote" i got yesterday was just for the price of the plugs not including labor.