I ran into something curious last week. Some of you may recall the fiasco I had when I attempted to change spark plugs at 68K on my 04. The bottom end of the plug seized in the heads requiring a removal of the heads to get the pieces out. So... I am now at 83K and thought I would remove the plugs and install a new set. Yeh... this is way overkill; but, they should come out ok.

My research shows that the 05 & 06 F150 use an Autolite HT2 while mine continues to call for the HT1. I suspect the only difference is the diameter of the sleeve below the threads; but, was just wondering if anybody has any additional info on any changes Ford may have made to the 5.4 3v between 04 and 05.

 

I believe the only difference between those 2 plugs is the heat range, 1 being colder.

 

Really. You must then think Ford made mods to the engine to require a hotter plug. Please clarify.